Inlined Template, so no function calling overhead. In the event if the functionality is critical to your system, it is actually beneficial to use an old strstr method. . The only remaining case I can see is in a macro body, and, well, C macros aren't really all that powerful. volatile). The link indicates "Microsoft Specific". Is there any reason on passenger airliners not to have a physical lock between throttles? My guess would be that it takes a lot of time to create those iterators. When the migration is complete, you will access your Teams at stackoverflowteams.com, and they will no longer appear in the left sidebar on stackoverflow.com.. double hashing to handle collisions); if you expect to often add items or if No symbols have been loaded for this document." A known problem with some #define macros. version available for String.IsNullOrWhiteSpace. What is the difference between String and string in C#? Thanks! This is an old question, and all of the old answers are incomplete or wrong. tape), the difference can be significant since the directory entry and inode are unlikely to be next to each other. There is, namely the _bittest intrinsic instruction. WebThe closest thing to a standard C way is opendir and readdir from dirent.h. This can only tell which process keeps an. It's also specific to the x86 architecture. stat() does look like a neater way to go. What you are asking is not possible in C (at least without compiler-specific extensions; it would be possible in C++, however). Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. @LudvigANorin: on such systems, the chances are that. Use stat(). Asking for help, clarification, or responding to other answers. How does the Chameleon's Arcane/Divine focus interact with magic item crafting? Please see the solution in this SO post -. Built-in Function: int __builtin_types_compatible_p (type1, type2) Why would Henry want to close the breach? @nailitdown: not really, you just need an extension method for Nullable. 48 -> 57 are numerics; 65 -> 90 are capital letters; 97 -> 122 are lower case letters Also. which is why i'm using "object". Why do American universities have so many general education courses? Since every function has concrete types for its parameters (except for varargs, I suppose), you don't need to check in the function body. The sizeof method seems to be a practical workaround solution for me. is just compiler sugar for the INullable type, so you could probably take an INullable as the parm and then jsut compare it to null (parm == null) and if not null compare to zero. always flatten your bools. This is really just an expansion of Freddy Rios' accepted answer only using Generics. How does the typecheck macro from the Linux kernel work? WebThe thing is, check if the list is empty is quite important, at least for me. Or more general: How do I compare two types so that compare(double1,double2) will evaluate to true, and compare(int,double) will evaluate to false. It's more undestandable, if you specify in regex, what your string SHOULD contain, and not what it MUST NOT. Making statements based on opinion; back them up with references or personal experience. No need(and not possible either) to check it at runtime. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Can't you cast both of them to a double (and add. That is a standard C interface, it's just standardized in POSIX and not in the C standard itself. However, this way, you would know that the problem is temporary, and to retry later. I want to be able to quit Finder but can't edit Finder's Info.plist after disabling SIP. How do I run all Python unit tests in a directory? The ^ is not the only error. Let me check it Is it cheating if the proctor gives a student the answer key by mistake and the student doesn't report it? What you can do is check the character code ranges. scanf allows regular expressions as far as I know. How do I remedy "The breakpoint will not currently be hit. If you want a non-regex ASCII A-z 0-9 check, you cannot use char.IsLetterOrDigit() as that includes other Unicode characters, and is unreliable/unstable with unicode scalar values. @BartoszKP Exactly, and thank you. Debian/Ubuntu - Is there a man page listing all the version codenames/numbers? JavaScriptSerializer - JSON serialization of enum as string. @JohannesSchaub-litb: one thing that's wrong with the, Let me be picky :) access() is not a standard function. See I'm using scanf %c to read a Y/N response, but later input gets skipped. I always get the message 'You didn't check it! Appropriate translation of "puer territus pedes nudos aspicit"? Well, if you are really looking for a better way, you can probably add another layer of abstraction on top of Rate. It comes is available out-of-the-box on Mac OS, Linux, all the BSDs, other UNIX/UNIX-like systems, and any other POSIX/SUS system. Question compares against "0" not an empty string. No, unfortunately, and if you think about it, that information would be worthless anyway since the file could become locked the very next second (read: short timespan). Let us say we want to know if 'temp' has Nth bit set or not. Add a new light switch in line with another switch? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. The std::search method within algorithm is the slowest possible. WebStack Overflow for Teams is moving to its own domain! As others have mentioned, you can't extract the type of a variable at runtime. It failed afterwards, but on a different issue. At what point in the prequels is it revealed that Palpatine is Darth Sidious? The rubber protection cover does not pass through the hole in the rim. http://msdn.microsoft.com/en-us/library/system.io.filestream.lock.aspx, FileStream.Unlock Where does the idea of selling dragon parts come from? The language is specifically designed not to care if char * points to something stored as int or char. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Can virent/viret mean "green" in an adjectival sense? rev2022.12.9.43105. In general, with C you're expected to know the types of your variable. Otherwise, the value of parameter is substituted.. This allows non A-Z letters such as Chinese charactersetc. I recommend the second approach because it won't end up creating an Array of the size equal to the range you want to check. I have WebStack Overflow for Teams is moving to its own domain! How do I check for an empty/undefined/null string in JavaScript? Is there any reason on passenger airliners not to have a physical lock between throttles? Which mechanism to use depends among other things on if you can choose the hash function and possible pick more than one (to implement e.g. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Passing variable number of arguments of different types in c. How to know if a variable is a function pointer in C? Check whether variable is number or string in JavaScript. How do I check that a number is float or integer? If you'd like to check if the argument exists, you can check if the # of arguments is greater than or equal to your target argument number. What's the difference between faking, mocking, and stubbing? What's the canonical way to check for type in Python? Simple. If you typed a character and pressed enter, then that input character would be read by line 1, and then '\n' would be read by line 2. I did not say that this answer is wrong. http://www.robertgamble.net/2012/01/c11-generic-selections.html. Allow non-GPL plugins in a GPL main program, Sed based on 2 words, then replace whole line with variable. If the regex would be correct there would be no need to invert the result. I can check that an object is not a class, not a module, not a traceback etc., but I am interested in a simple solution. Not the answer you're looking for? This built-in function ignores top level qualifiers (e.g., const, pip install -vvv if you will carefully check the output, you will see it might be going to some URL like pypi.org or may be pypi.python.org. If obj is null then the obj.ToString() will result in a null reference exception. Find centralized, trusted content and collaborate around the technologies you use most. WebRsidence officielle des rois de France, le chteau de Versailles et ses jardins comptent parmi les plus illustres monuments du patrimoine mondial et constituent la plus complte ralisation de lart franais du XVIIe sicle. Building a type description table for a struct at compile time, How to create a new object instance from a Type. @Christoph You will find out when someone does something like 'typedef char BOOL' and you try to pass the output of CHECK_BIT as a BOOL argument that happens to check a bit past the 8th one. When would I give a checkpoint to my D&D party that they can return to if they die? Examples of frauds discovered because someone tried to mimic a random sequence, Counterexamples to differentiation under integral sign, revisited. Is there a higher analog of "category with all same side inverses is a groupoid"? A more modern approach as suggested in the comments: @Dennis: git checkout , for example git checkout origin/test results in detached HEAD / unnamed branch, while git checkout test or git checkout -b test origin/test results in local branch test (with remote-tracking branch origin/test as upstream) Jakub Narbski Jan 9 Debian/Ubuntu - Is there a man page listing all the version codenames/numbers? thanks for your help in advance! Sometimes it's good to explore other views. rev2022.12.9.43105. I always get the message 'You didn't check it! Running unittest with typical test directory structure, Mocking and unit testing implementation dependencies. We start from 0th possition, which is, @user21714 I guess u meant std::bitset<8 * sizeof(int)>. That might be (and is not, because modern processors detest bits and jumps). It depends what you're going to do based on the presence or absence of the file. stat() will fail if the file doesn't exist, otherwise most likely succeed. So your answer has multiple errors! (an exception will be thrown). types type1 and type2 (which are types, not expressions) are We do not currently allow content pasted from ChatGPT on Stack Overflow; read our policy here. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. @con-f-use Macros work at compile-time. If it is another kind of issue with file access then we should just propagate exception. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Web@HunanRostomyan Good question, and honestly, no, I do not think that there is. Ho hum. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. WebI just tested and using shopt -u expand_aliases ignores/hides aliases (like the alias ls='ls -F' mentioned in another answer) and shopt -s expand_aliases resolves them via command -v.So perhaps it should be set prior to the check and unset after, though it could affect the function return value if you don't capture and return the output of the command call explicitly. Use it only if you don't need your code to be portable. And you are mistaken, C has dynamic types that are only determined at run time: variable modified (VM) types. Why is processing a sorted array faster than processing an unsorted array? Examples of frauds discovered because someone tried to mimic a random sequence. Using the correct options to open() is usually the best way of dealing with the problems, but it can be tricky formulating the right options. Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_u64 on Intel CPUs, Bracers of armor Vs incorporeal touch attack. WebIn general, with C you're expected to know the types of your variable. Every variable has an explicitly declared and unchangeable type, and you supposed to use this knowledge. My comment refers to the comment of John Saunders above. WebThere are two ways we can solve this: Easy and non-secure: 1. check which URL is hit by pip to download the package. How to check if a struct member exists in C? Yeah, I know I don't "have" to do it this way. WebThere are two ways we can solve this: Easy and non-secure: 1. check which URL is hit by pip to download the package. I want to do one thing with the "struct a" variables and the other with the "struct b" variables. 1. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. And in case you're using C++, you could (should) write a template instead of a macro. rev2022.12.9.43105. (or use stdbool.h) My recommendation is to use the Strict Not Version. b) Check if an element has zero width / height / opacity or display:none / visibility:hidden in inline styles. If you want to check for existence and create the file if it doesn't exist, atomically so that there are no race conditions, then use this: Yes. Find centralized, trusted content and collaborate around the technologies you use most. You do not allow comma and space, 3.) Get same day delivery or save 35% with repeat delivery or 10% on curbside pickup at your local Petco. Effect of coal and natural gas burning on particulate matter pollution. I'd short cut the process and check for a null obj at the start of your helper function. See the man page forstat(2). If you have the value the OP posted: 1011110 and you want to know if the bit in the 3rd position from the right is set, just do: Or something a bit prettier that may be more easily interpreted by future readers of the code: You could "simulate" shifting and masking: if((0x5e/(2*2*2))%2) One approach will be checking within the following condition: note this hw dependent and assumes this bit order 7654 3210 and var is 8 bit. How do I tell if this single climbing rope is still safe for use? Is the EU Border Guard Agency able to tell Russian passports issued in Ukraine or Georgia from the legitimate ones? Since every function has concrete types for its parameters (except for varargs, I suppose), you don't need to check in the function body. Obtain closed paths using Tikz random decoration on circles. Of course, that doesn't make it more portable. 2.) To invert a bool use the "not" operator "!". I want to be able to quit Finder but can't edit Finder's Info.plist after disabling SIP. To make it work it is necessary to define: You can also use R_OK, W_OK, and X_OK in place of F_OK to check for read permission, write permission, and execute permission (respectively) rather than existence, and you can OR any of them together (i.e. Why is Singapore considered to be a dictatorial regime and a multi-party democracy at the same time? When the migration is complete, you will access your Teams at stackoverflowteams.com, and they will no longer appear in the left sidebar on stackoverflow.com.. For example, here's a macro that will check if some input is compatible with another type: This can also be used on other types, including structs. Usually when you want to check if a file exists, it's because you want to create that file if it doesn't. divs, muls and mods are the three most expensive functions. To learn more, see our tips on writing great answers. Yes but that is not checkable in C and works only at compile-time not at run-time. It is not a standard part of C. It's typically used to write macros that only evaluate their arguments once, eg (from the GCC manual): The typeof keyword lets the macro define a local temporary to save the values of its arguments, allowing them to be evaluated only once. http://msdn.microsoft.com/en-us/library/system.io.filestream.unlock.aspx. Find centralized, trusted content and collaborate around the technologies you use most. I recommend the second approach because it won't end up creating an Array of the size equal to the range you want to check. Is it correct to say "The glue on the back of the sticker is dying down so I can not stick the sticker to the wall"? msdn.microsoft.com/en-us/library/windows/desktop/, gist.github.com/mlaily/9423f1855bb176d52a327f5874915a97, learn.microsoft.com/en-us/dotnet/standard/design-guidelines/, http://msdn.microsoft.com/en-us/library/system.io.filestream.lock.aspx, http://msdn.microsoft.com/en-us/library/system.io.filestream.unlock.aspx, stackoverflow.com/posts/3202085/revisions, Please see my answer here for more information. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. https://gcc.gnu.org/onlinedocs/gcc-3.4.5/gcc/Other-Builtins.html. The following is a bit more verbose, but it's for ease of understanding rather than for code golf. Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content, Syntax and Sample Usage of _Generic in C11. The example in this entry goes: However, bit members in structs have practical drawbacks. 1. As reported also by Wikipedia, in 1990 Michael Keith and Tom Craver published an expression to minimise the number of keystrokes needed to enter a self-contained function for converting a Gregorian date into a numerical day of the week.. You could argue the same for access rights though it would of course be more unlikely. So if you just want to make sure that there is someting of value in the string, this is what I have used in C#: Thanks to Chopikadze for the basic structure. And then, as you say, wait, or deal with it in another way. is shorthand Nullable so by adding the extension to Nullable we get the method in int?, double?, bool? The following script demonstrates how this works. WebThe closest thing to a standard C way is opendir and readdir from dirent.h. If it is, then it's not a class instance. How to register multiple implementations of the same interface in Asp.Net Core? Since typeof is a compiler extension, there is not really a definition for it, but in the tradition of C it would be an operator, e.g sizeof and _Alignof are also seen as an operators. I added a complete and correct answer. Your regex does not permit spaces and it only SEARCHES for any word INSIDE the given string. Then you would be able to check it at runtime: As another answer mentioned, you can now do this in C11 with _Generic. is faster than all the other options, since. You could just use parameter expansion: ${parameter:-word} If parameter is unset or null, the expansion of word is substituted. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Instead of using interop you can use the .NET FileStream class methods Lock and Unlock: FileStream.Lock You can check the return value of the atoi() function to know whether the input given is an integer or not. from the comp.lang.c FAQ. From the Visual C++ help, I'd tend to go with. Gnu GCC has a builtin function for comparing types __builtin_types_compatible_p. Basically, I have a function that operates on variables of type "struct a" and "struct b". The following boolean expression will give true if bit is set, 0 otherwise. If you'd like to check if the argument exists, you can check if the # of arguments is greater than or equal to your target argument number. How do I remove all non alphanumeric characters from a string except dash? To learn more, see our tips on writing great answers. How do I print in Rust the type of a variable? The comma is not an alphanumeric character! if else can be done easily with a ternary: The & operation is done on values not on the internal representation. The std::search method within algorithm is the slowest possible. A couple of things worth mentioning here - bits[3] will give you the 4th bit - counting from the LSB to MSB. E.g. This is the exact issue I just encountered while using it like, The double negate might be "costly", but if. The expression does preserve neither y nor d, and returns a zero-based index representing the day, starting with Otherwise, the value of parameter is substituted.. To put it loosely, it will give you the 4the bit counting from right to left. from the comp.lang.c FAQ. originally: The issue with this method is that it accept all type of variable in an uncontrolled way. It comes is available out-of-the-box on Mac OS, Linux, all the BSDs, other UNIX/UNIX-like systems, and any other POSIX/SUS system. How can i check exist of a file base on the user input. Debian/Ubuntu - Is there a man page listing all the version codenames/numbers? if it is, just add trusted host option to the command like below: To add to that, if you insist on doing this, add a static assert to ensure the sizes never become the same accidentally: In my case of comparing structs they both have the same members except for one having two additional double member. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. I have researched and stumbled into CMock, GMock, and CPPUMock, but many of these seemed to only work on their respective Unit Testing framework. CGAC2022 Day 10: Help Santa sort presents! i was trying to read a 32-bit integer which defined the flags for an object in PDFs and this wasn't working for me, the operand & returns an integer with the flags that both have in 1, and it wasn't casting properly into boolean, this did the trick, where "pos" is defined as 2^n (i.g. This answer is terrible. [continuing] Rather more esoterically, on POSIX systems, access() checks whether the real UID and real GID, rather than the effective UID and effective GID. WebShop Petco for what your pet needs, when they need it. WebThe closest thing to a standard C way is opendir and readdir from dirent.h. The variable name can be got out by the #, One possible way is to have your variables names prepend your variable definitions with the type information. You can see if the file is locked by trying to read or lock it yourself first. They other way around is by replacing the void* by an union , this way the structure while only accept specific data type defined inside the union list . Yes, but the standalone check for whether a file is locked is useless, the only correct way to do this is to try to open the file for the purpose you need the file, and then handle the lock problem at that point. How do I detect unsigned integer overflow? Web@HunanRostomyan Good question, and honestly, no, I do not think that there is. Well, I was doing a kind of the same thing in my original answer till somebody decided to simplify it:), You should consider a Using block for file. Generally, a download manager enables downloading of large files or multiples files in one session. Counterexamples to differentiation under integral sign, revisited, 1980s short story - disease of self absorption. Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content, int? Asking for help, clarification, or responding to other answers. @configurator: when nullable types are boxed, they're boxed as the underlying struct, i.e., so this will not construct a null-values nullable, but a default-valued non-nullable struct. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. How to write a LINQ to only get rows that match a certain condition dependant on columns shown? It depends what you're going to do based on the presence or absence of the file. Indeed, if the script is designed to run with strictly controlled input, the check might be a little unnecessary. How did muzzle-loaded rifled artillery solve the problems of the hand-held rifle? My guess would be that it takes a lot of time to create those iterators. It comes is available out-of-the-box on Mac OS, Linux, all the BSDs, other UNIX/UNIX-like systems, and any other POSIX/SUS system. and I am looking to implement a Mock Generator or framework for some of the more complex modules dependent on other modules. Appropriate translation of "puer territus pedes nudos aspicit"? You can use a Bitset - http://www.cppreference.com/wiki/stl/bitset/start. Here you can find explanation which statements from standard and which GNU extensions above code uses. Why would Henry want to close the breach? Here is what the poster was originally looking for. ((var) & (1 << (pos))). How to make an output function similar to Python's in C? It took some time until I understood what you mean. Since C doesn't support overloading and the void pointer losses its type information I need to check for type. Although I quite like the accepted answer, I think that, for completeness, this option should be mentioned as well: This should not influence your decision, though, since these kinds of micro-optimization are unlikely to make any difference. Unfortunately, it does not allow regular expressions: the syntax is misleadingly close, but there is nothing even remotely similar to the regex in the implementation of scanf.All that's there is a support for character classes of regex, so %[] is treated implicitly as []*.That's why Keep in mind, i think you're right that eliminating null values at some earlier stage would've been the way to go, Not exactly. this code return always false, because the symbole ^ means that's this string doesn't contains any alphanumeric caractere, you need to delete the this ^. Whats the best way to check if a file exists in C++? This is crazily stupid, but if you use the code: and you use the -Wall flag while compiling, then gcc will kick out a warning of that it expects an argument of 'unsigned int' while the argument is of type '____'. 48 -> 57 are numerics; 65 -> 90 are capital letters; 97 -> 122 are lower case letters This one provides a better solution. A variation of DixonD's excellent answer (above). And then, as you say, wait, or deal with it in another way. @con-f-use, it's a great workaround until you add a member, the sizes become equal, and suddenly it's always taking the. Find centralized, trusted content and collaborate around the technologies you use most. You can't declare a function which operate on type A or type B, and you can't declare variable which hold type A or type B. You can refactor your code toward a better pattern or to a better structure. It's possible to identify a system context well enough to get value from a lock test. Implementing INotifyPropertyChanged - does a better way exist? Knowing that might give us some other way of giving you good advice. See I'm using scanf %c to read a Y/N response, but later input gets skipped. WebThe shortest way to do that would be: do { // Something } while (*url); Basically, *url will return the char at the first position in the array; since C strings are null-terminated, if the string is empty, its first position will be the character '\0', whose ASCII value is 0; since C logical statements treat every zero value as false, this loop will keep going while the first position Look in the source code, it states right there that doubleVar is a double. Since typeof is a compiler extension, there is not really a definition for it, but in the tradition of C it would be an operator, e.g sizeof and _Alignof are also seen as an operators. Many web browsers, such as Internet Explorer 9, include a download manager. Why did the Council of Elrond debate hiding or sending the Ring away, if Sauron wins eventually in that scenario? and is unreliable/unstable with unicode scalar values. I'm sure other architectures have similar options. This means that, even if, hypothetically, there was a type comparison extension, it would only work properly when the types are known at compile time (ie, it wouldn't work to test whether two void * point to the same type of data). 1. Simply, you can't). In case you need a simple truth value, it should be !! What you can do is check the character code ranges. I have include some 'c' code that works just fine. @Christoph You will find out when someone does something like 'typedef char BOOL' and you try to pass the output of CHECK_BIT as a BOOL argument that happens to check a bit past the 8th one. Jonathan Leffler is right, this example requires O_EXCL to work as written. Thanks for contributing an answer to Stack Overflow! Get same day delivery or save 35% with repeat delivery or 10% on curbside pickup at your local Petco. My question is their a Mock framework compatible with the Check C unit testing framework that someone knows or attempted? WebShop Petco for what your pet needs, when they need it. Is there a verb meaning depthify (getting more depth)? Is there such a way to check if bit 3 in temp is 1 or 0 without bit shifting and masking. Could either of you point to documentation regarding the failure after 2 GB? I am currently using a C-only Unit Testing framework called Check C. More information can be found here: https://libcheck.github.io/check/ and I am looking to implement a Mock Generator or framework for some of the more complex modules dependent on other modules. If you typed a character and pressed enter, then that input character would be read by line 1, and then '\n' would be read by line 2. Where does the idea of selling dragon parts come from? To learn more, see our tips on writing great answers. Are the S&P 500 and Dow Jones Industrial Average securities? On storage devices with bad seek time (e.g. Obviously this code example is far from perfect and cannot be used directly but i tried to explain in a way as clear as possible the logic and the the idea that i proposed ;). double hashing to handle collisions); if you expect to often add items or if if it is, just add trusted host option to the command like below: So I should be save if I do "if(sizeof(a)>sizeof(b))" independent of architecture or other stuff. If the programmer decide to pass a pointer with an type which is not already defined inside the ptr_data union{} , it will throw an error. atoi() function returns the integer number if the input string contains integer, else it will return 0. test.sh #!/usr/bin/env bash if [ $# -ge 3 ] then echo script has at least 3 arguments fi produces the following output As zendar wrote, it is nice to use the Socket.Poll and Socket.Available, but you need to take into consideration that the socket might not have been initialized in the first place.This is the last (I believe) piece of information and it is supplied by the Socket.Connected property. You can check the return value of the atoi() function to know whether the input given is an integer or not. Let's not vote down this answer. Also consider whether O_TRUNC or O_EXCL or O_APPEND should be used. Your code has 5 errors: 1.) Sed based on 2 words, then replace whole line with variable. See also discussions on EAFP The sizeof idea was simply a better workaround for me. Many web browsers, such as Internet Explorer 9, include a download manager. In response to Edit #1: have you considered using function pointers (like a vtable) to solve your issue? How to check certain bits of a variable in C++? This solution is extremely wasteful on resources and unintuitive. @cnicutar I know what a macro is. Also, what is the alternative in such cases? Remember, the '?' How could my characters be tricked into thinking they are on Mars? It should be deleted. It is a seriously tricky bug to track down and caused at least one massive security breach. Are there breakers which can be triggered by an external signal and have to be reset by hand? To support the Restart Manager API, that information is now tracked. central limit theorem replacing radical n with n, []* - could contain any number of characters between brackets, \s - any space characters (space/tab/etc.). vanilla js /** * @description determine if an array contains one or more items from another array. There could be reasons that aren't temporary. Both stat() and access() suffer from the TOCTOU vulnerability (so does lstat(), but fstat() is safe). In the event if the functionality is critical to your system, it is actually beneficial to use an old strstr method. @bdonlan I almost feel bad not accepting your answer. Find centralized, trusted content and collaborate around the technologies you use most. Here's a variation of DixonD's code that adds number of seconds to wait for file to unlock, and try again: You could call LockFile via interop on the region of file you are interested in. Edit: Just read Mecki's post. WebThe shortest way to do that would be: do { // Something } while (*url); Basically, *url will return the char at the first position in the array; since C strings are null-terminated, if the string is empty, its first position will be the character '\0', whose ASCII value is 0; since C logical statements treat every zero value as false, this loop will keep going while the first position If you want a non-regex ASCII A-z 0-9 check, you cannot use char.IsLetterOrDigit() as that includes other Unicode characters, and is unreliable/unstable with unicode scalar values. It is a seriously tricky bug to track down and caused at least one massive security breach. You should use the extension method; while it is readable at the moment of writing, this little code nuggets requires a fraction of thought, meaning if you try to read code and it uses it - you are distracted from your main problem. The Restart Manager API is available beginning with Windows Vista and Windows Server 2008 (Restart Manager: Run-time Requirements). Follow answered Feb 14, 2018 at 6:59. WebThe thing is, check if the list is empty is quite important, at least for me. * @param {array} haystack the array to search. test bit by right shift same speed as left shift? How could my characters be tricked into thinking they are on Mars? your solution works for one property, i should've specified i have many properties of the same item to check for null/zero. Thanks anyways. test.sh #!/usr/bin/env bash if [ $# -ge 3 ] then echo script has at least 3 arguments fi produces the following output Checking single bits in a bitmask using std::pow, a function to check if the nth bit is set in a byte. This is a code-only answer. Strict Not Version Is this an at-all realistic configuration for a DHC-2 Beaver? The C runtime library will take care of that for you: your program will see just '\n' for newlines. It failed afterwards, but on a different issue. Why does the distance from light to subject affect exposure (inverse square law) while from subject to lens does not? This is because access only has to look at the directory entry, while stat has to look up the inode as well. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. How do I tell if this single climbing rope is still safe for use? I do think that this one would be faster since instead of checking through the entire string, it would stop at the first instance of a word character and return a true. There are lot more functions to convert a string into long, double etc., Check the standard library "stdlib.h" for more. (or use stdbool.h), +1 for mentioning it's starting from 0 since I suspect the OP was thinking 1-based and the accepted answer will get him into trouble. Also, you need to specify the mode as a third argument: open(lock, O_CREAT | O_WRONLY | O_EXCL, S_IRUSR | S_IWUSR), It should be noted that this is only as safe as the filesystem is POSIX compliant; in particular, old versions of NFS have the very race condition O_EXCL was supposed to avoid! Ready to optimize your JavaScript with Rust? Why should I use a pointer rather than the object itself? So expression returns true, indicating 3rd bit is set. Is it correct to say "The glue on the back of the sticker is dying down so I can not stick the sticker to the wall"? 10 down-votes would be more adequate. (If this warning doesn't appear, then your variable is of type 'unsigned int'.). * @param {array} haystack the array to search. Since typeof is a compiler extension, there is not really a definition for it, but in the tradition of C it would be an operator, e.g sizeof and _Alignof are also seen as an operators. What is the difference between Nullable.HasValue or Nullable != null? Share. WebIn general, with C you're expected to know the types of your variable. warning? always flatten your bools. @RenniePet The following page should be more helpful: What's the purpose of bit-masking here, if you compare the result to a constant? Following an example of how to handle flags in an integer. Detects IsBitSet(int32,int64) calls without my knowledge & consent. How do I tell if this single climbing rope is still safe for use? Effect of coal and natural gas burning on particulate matter pollution. Unfortunately, it does not allow regular expressions: the syntax is misleadingly close, but there is nothing even remotely similar to the regex in the implementation of scanf.All that's there is a support for character classes of regex, so %[] is treated implicitly as []*.That's why Before you do that, read the comments below. WebWhat I did was download the JDK from here, start a windows command prompt (windows+r CMD) and set the environment variable JAVA_HOME to c:\Program Files\Java\jdk-14 with: set JAVA_HOME="c:\Program Files\Java\jdk-14" Then run what I wanted to run. Not the answer you're looking for? Even after deleting it, it will still be wrong. If you want a shorter version you can write: @"^[\w\s,]+$", I added an answer that avoids regex, and only accepts. Which mechanism to use depends among other things on if you can choose the hash function and possible pick more than one (to implement e.g. "== true ? The only remaining case I can see is in a macro body, and, well, C macros aren't really all that powerful. This is the only correct answer on this page. Ready to optimize your JavaScript with Rust? However I prefer stat(), as if the file exists it will immediately get me lots of useful information (when was it last updated, how big is it, owner and/or group that owns the file, access permissions, and so on). Connect and share knowledge within a single location that is structured and easy to search. But I usually write: According to this description of bit-fields, there is a method for defining and accessing fields directly. This is the only practical solution so far. What's the strategy for handling CRLF (carriage return, line feed) with Git? If I want to know if 3rd bit is set or not, I get. by comparision tests, ands and shifts are among the cheapest - some of the few you might actually get done in less than 5 cycles. Let me check it Use std::bitset, @Christoph You will find out when someone does something like 'typedef char BOOL' and you try to pass the output of CHECK_BIT as a BOOL argument that happens to check a bit past the 8th one. See I'm using scanf %c to read a Y/N response, but later input gets skipped. As zendar wrote, it is nice to use the Socket.Poll and Socket.Available, but you need to take into consideration that the socket might not have been initialized in the first place.This is the last (I believe) piece of information and it is supplied by the Socket.Connected property. LATGbits.LATG0=((m&0x8)>0); //to check if bit-2 of m is 1, the fastest way seems to be a lookup table for masks. What is a cross-platform way to get the home directory? Would it be possible, given current technology, ten years, and an infinite amount of money, to construct a 7,000 foot (2200 meter) aircraft carrier? Share. Why is it so much harder to run on a treadmill when not holding the handlebars? Does balls to the wall mean full speed ahead or full speed ahead and nosedive? As for typeof: First, typeof is a GCC extension. atoi() function returns the integer number if the input string contains integer, else it will return 0. Strict Not Version What you can do is check the character code ranges. You need to allow also the comma, which is not alphanumeric, so your function has the wrong name. What are the criteria for a protest to be a strong incentivizing factor for policy change in China? Long ago it was impossible to reliably get the list of processes locking a file because Windows simply did not track that information. Would it be possible, given current technology, ten years, and an infinite amount of money, to construct a 7,000 foot (2200 meter) aircraft carrier? Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content. Jack Fairfield. Is there a better way than simply trying to open the file? How to delete a specific file from folder using asp.net. JavaScript checking for null vs. undefined and difference between == and ===. The ^ as the FIRST character and the $ as the LAST character are missing. thanks for your help in advance! What do we get when, OK, got it. Graeme Perrow's answer is good if you don't want to create that file, but it's vulnerable to a race condition if you do: another process could create the file in between you checking if it exists, and you actually opening it to write to it. My recommendation is to use the Strict Not Version. (Don't laugh this could have bad security implications if the file created was a symlink!). Check your email for updates. This does not work for files larger than 2GB on all systems. I think that access() function, which is found in unistd.h is a good choice for Linux (you can use stat too). Have you considered if there's some script inside that might use the result from the for loop? One approach, like you describe in your question, is a process of exclusion, check if it isn't what you want. NOTE we don't need to check default(T) for null since we are dealing with either value types or structs! All of the "You can't do that without transactions" comments may raise a valid concern, but are not useful since they're pretending that the functionality isn't there or is somehow hidden when it's not. WebBasically you need an char array (an array of characters) big enough to store the entire string with a terminating (ending) '\0' character. "You could however check the size of a variable using the sizeof() function". C#: Check if a file is not locked and writable. You are most likely safe enough using variable === null which I just tested here in this JSFiddle.The reason I also used ` && typeof variable === 'object'` was not only to illustrate the interesting fact that a null value is a typeof object, but also to keep with the flow of the other checks. WebWhat I did was download the JDK from here, start a windows command prompt (windows+r CMD) and set the environment variable JAVA_HOME to c:\Program Files\Java\jdk-14 with: set JAVA_HOME="c:\Program Files\Java\jdk-14" Then run what I wanted to run. An other way around to control the datatype could be done using an union with predefined type. 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