But I was just wondering if there's any way by which we can calculate the size of the pointer without the sizeof operator. You can use the following macro, taken from here: The idea is to use pointer arithmetic ((&(var)+1)) to determine the offset of the variable, and then subtract the original address of the variable, yielding its size. How to find the size of a variable without using sizeof. You can try and avoid the monsters of undefined behaviour by doing something like this. Swap two Strings without using temp variable in C#. When adding multiple answers to a question, please include an explanation to them which explains the difference. But here I am interested in calculating the size of structure in C without using the sizeof() operator. But unless you're writing a compiler it's surprising you don't want to just use sizeof, which is the One Right Way to solve this problem. This takes into account that a C++ byte is not always 8 binary bits, and that only unsigned types have well defined overflow behaviour. Find the difference between the above 2 pointers using a type cast. WebThe sizeof() datatype returns the size of a data type. // without using For some special cases you could generate un-portable code that used some other heuristic to understand the size of particular objects[*] (probably by making them keep track of their own size), but you'd have to do all the bookkeeping yourself. But it is my recommendation to use the sizeof() operator to calculate the size of the structure in a program whenever you need to calculate the size of the structure. Lets say you need to find the size of int datatype . Follow-up question: I want to include a header file I wrote, without using any preprocessor directives, of course. Does http_proxy automatically work in Linux for all applications? Using flutter mobile packages in flutter web. Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content, How to find the size of a variable without using sizeof. We can find the size of an array More tips. How to change the stack size using ulimit or per process on Mac OS X for a C or Ruby program? The usage of sizeof is simple. Since I want a generic solution I am simply mentioning that variable 'i' can be of any one of the datatypes namely int, char, float or double. (adsbygoogle = window.adsbygoogle || []).push({}); When doing pointer math I like to cast the pointers to intptr_t or uintptr_t not char*. You will receive mail with link to set new password. How to find the size of the L1 cache line size with IO timing measurements? People also ask. Interview questions on bitwise operators in C. 10 questions about dynamic memory allocation. One simple way of doing this would be using arrays. Please enter your email address. Why do some airports shuffle connecting passengers through security again. . How do I arrange multiple quotations (each with multiple lines) vertically (with a line through the center) so that they're side-by-side? What is the size of operator? What does sizeof (function(argument)) return? TabBar and TabView without Scaffold and with fixed Widget. How can you find the size of a datatype without creating a variable or pointer, or using sizeof of the datatype? document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); About Are defenders behind an arrow slit attackable? It's basically defined as the smallest individually addressable unit of memory. How does the compiler allocate memory without knowing the size at compile time? WebAlthough the standard says "The sizeof operator shall not be applied to an expression that has function type" (6.5.3.4/1), in GNU C, the result of doing this is well defined: "sizeof is also allowed on void and on function types, and returns 1" ~ GCC, 6.23 Arithmetic on void- and Function-Pointers Also have a look at: Why is the size of a function in C always 1 byte? WebThe idea is to use pointer arithmetic ((&(var)+1)) to determine the offset of the variable, and then subtract the original address of the variable, yielding its size. Next in this series: how to obtain the address-of without using an ampersand. The correct answer to this interview question is "Why would I want to do that, when sizeof() does that for me, and is the only portable method of d The word "byte" does not always mean "8 bits". Key point is when a pointer is incremented, it actually moves by the size equal to the object it is pointing, so here the size of the class (of which the object it is pointing to). WebWhat does variable in size mean? How to portably print a int64_t type in C. Add a new light switch in line with another switch? The possibility of padding prevent all hopes without the knowledge of the rules used for introducing it. And those are implementation dependent. Why of course? About us Articles Contact Us Online Courses, 310, Neelkanth Plaza, Alpha-1 (Commercial), Greater Noida U.P (INDIA). I mean how about writing our own sizeof operator. 8-bit bytes are by far the most common, but there could be (and have been!) Japanese girlfriend visiting me in Canada - questions at border control? Swapping two variables without using third variable, Find minimum cost to travel to the destination, Find kth largest element in running stream of numbers. systems with 9-bit and even 36-bit bytes, and a system with 32-bit bytes is conceivable, if it doesn't already exist. How to get the size of a const char pointer, Getting the size of a malloc only with the returned pointer, Size of short, int, long, float, double long, double, char. The correct answer to this interview question is "Why would I want to do that, when sizeof() does that for me, and is the only portable method of doing so?". How can you find the size of a datatype without creating a variable or pointer, or using sizeof of the datatype? It is also an important interview question that is generally asked by the interviewer to check the. rev2022.12.11.43106. Does illicit payments qualify as transaction costs? Output. Calculating the size of structure in bytes without using sizeof. How to calculate the Size of Folder using C#? Lost your password? If you found any error or any queries related to the above program or any questions or reviews , you wanna to ask from us ,you may Contact Us through our contact Page or you can also comment below in the comment section.We will try our best to reach up to you in short interval. Look, sizeof is the language facility for this. Your email address will not be published. How can I move to a pointer position directly without using the ++ operator? Using the sizeof() operator we can calculate the size of the structure straightforward to pass it as a parameter. I am a professional blogger, present started writing artilces on job description template, Your email address will not be published. No. No, we can even find the size of entire expressions using the operator. Get the base address of the variable 'Var' using address of(&) operator. Required fields are marked *. How do I determine the size of an object in Python? I will make a better assumption saying. This trick is highly Why does it matter if this person should use something or not? Code Explanation. Write a C program to find size of variables using sizeof() operator. To get the size of a variable, sizeof is used. By this code script the size of any data can be calculated without sizeof operator.Just change the float in line 1 with the type whose size you want to calculate. if X is a variable: #define SIZEOF(X) (unsigned int)( (char *)(&X+1)-(char *)(&X) ) sizeof() is an operator in c programming language, which is used to get the occupied size by the variable or value. clone system call's argument stores in stack or somewhere else? Greedy Solution to Activity Selection Problem. Using the sizeof () It's been ages since I wrote any C code and I was never good at it, but this looks about right: I'm sure someone can tell me plenty of reasons why this is wrong, but it prints a reasonable value for me. WebHow would you determine size of a variable without using sizeof? In order to use sizeof the zoperator, you can pass variable to the operator. int x; x = sizeof (int); To get the size of a variable, without using the sizeof, try the following code . You can use the following macro, taken from here: The idea is to use pointer arithmetic ((&(var)+1)) to determine the offset of the variable, and then subtract the original address of the variable, yielding its size. You are given have a datatype, say X in C. The requirement is to get the size of the datatype, without declaring a variable or a pointer variable. Available since C89 solution that in user code: Easy enough to do using standard code as hinted by @steve jessop, which expands to an integer constant expression that has type size_t, the value of which is the offset in bytes, to the structure member , from the beginning of its structure C11 7.19 3. When can I find out more? Ready to optimize your JavaScript with Rust? How do I determine the size of my array in C? Why isn't sizeof for a struct equal to the sum of sizeof of each member in C/C++? WebIn C language, sizeof () operator is used to calculate the size of structure, variables, pointers or data types, data types could be pre-defined or user-defined. A recursive method to find depth of a any(not necessarily complete) Binary tree, Swap number digit order by separate a number into arrays and then merge, C : Passing bi-dimensional array of pointers as argument, Why does quicksort take longer when sorted in descending order vs ascending order, Do the names of the args passed to main() matter, Should you free at the end of a C program. sizeof (int) [required] sizeof foo_variable [not required]. So the size of the InfoData will be 12 bytes due to the padding bytes. Perl regex to find the name of a packed struct without using variable length lookbehind? WebHere is how to find size of a structure without sizeof operator. The size of a variable depends on its type, and C++ has a very convenient operator called sizeof that tells you the size in bytes of a variable or a type. For example, if you have - AticleWorld, What is importance of struct hack in c? I have a data type, say X, and I want to know its size without declaring a variable or pointer of that type and of course without using sizeof operator. Your email address will not be published. In this example, you will learn to evaluate the size of each variable using sizeof operator. @KeithThompson: Oops yes! Create a pointer to structure and assign the NULL pointer. Note: Structure padding also affects the size of the structure in C. When we increment the pointer then pointer increases a block of memory (block of memory depends on pointer data type). How is the size of a variable length array computed at runtime in C99? This padding is an extra memory which will not be used to store anything, but to optimize the read/write of individual fields of a structure variable. Why would Henry want to close the breach? I am trying to find the size of an integer. How to find the size of an int[] in C/C++? A lot of these answers are assuming you know what your structure will look like. Here is the generic approach to find size of any variable without using sizeof operator: Suppose we want to find the size of variable 'Var' of data type D(for example an integer variable 'Var'). WebHere's a trick for finding the size of a variable without using sizeof--not something you'd generally do, but it demonstrates the ability to use pointer arithmetic. I am trying to find the size The trick is to make a pointer object, save its address, increment the pointer and then subtract the new address from the previous one. Write a C program to find size of variables using sizeof () operator. Also sizeof is an operator and does not require parentheses unless operating on a type. For example, if you have an int16_t i variable located at 0x0002, you would be subtracting 0x0002 from 0x0006, thereby obtaining 0x4 or 4 bytes. The sizeof( ) operator can be used to find the size of data types and expressions. Hope this helps.. Is MethodChannel buffering messages until the other side is "connected"? Variable-size data is data whose size is not known at compile time or whose size can change at run time. However, I don't really see a valid reason not to use sizeof, but I'm sure you must have one. I believe this interview question is intended to ask you to think outside the box. How to check if widget is visible using FlutterDriver. Declare 2 pointer variable of the same type and assign the address of the variable to them and then increment one of them. How to swap two numbers without using the third or a temporary variable using C Programming? Now, we know for the fact that in arrays elements of the same datatype are stored in a contiguous block of memory. //don't try to do this with doubles. In C language, sizeof() operator is used to calculate the size of structure, variables, pointers or data types, data types could be pre-defined or user-defined. Using the sizeof() operator we can calculate the size of the structure straightforward to pass it as a parameter. Guest Article Connect and share knowledge within a single location that is structured and easy to search. I have working experience of different microcontrollers (stm32, LPC, PIC AVR and 8051), drivers (USB and virtual com-port), POS device (VeriFone) and payment gateway (global and first data). It is a compile-time execution operator. To get the size of a variable, sizeof is used. 5. https://aticleworld.com/pointer-arithmetic/, What is flexible array member in C? @2501 Padding perhaps. This program declares 4 variables of type int, float, double and char. Why do quantum objects slow down when volume increases? WebHere we are going to do a pointer arithmetic trick to get the size of a variable. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. C. Aricent. Asking for help, clarification, or responding to other answers. sizeof(int); For double datatype Is this possible? Create pointers to the structure and assign the address of the first and second element of the array. Required fields are marked *. Try this: int a; The question asks how to do this "without declaring a variable or pointer of that type.", There are multiple issues with that answer. How to copy local variable to global variable if both have the same names in C without using a third variable? See, Method-1 in solution). WebBy this code script the size of any data can be calculated without sizeof operator.Just change the float in line 1 with the type whose size you want to calculate. You could puzzle it out by reading the ABI for your particular processor, which explains how structures are laid out in memory. How do you find the size of a variable There may be padding in between the members. How to find the position of the only-set-bit in a 64-bit value using bit manipulation efficiently? In the previous article all about the pointer, we have read that using the pointer subtraction we can calculatethe number of bytes between the two pointers. How can I do that? just comment what program do u want , we provide u better support .Thanks. invalid application of 'sizeof' to incomplete type 'struct array[]', How to find the size of a variable without using sizeof. Well, I am an amateur..but I tried out this problem and I got the right answer without using sizeof. I think that parentheses is good for the readability and there is no side effect for parentheses. WebFind size of variables using sizeof () operator. The entire point of this website is to help others out, not to pick apart a question until it conforms to what we want. Look into the compiler sources. Stay tuned! To understand this better, let us look at a few examples. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive programming/company interview Questions. How to share internet from mobile to PC without hotspot? Can we keep alcoholic beverages indefinitely? Thanks mark for the suggestion. You could puzzle it out by reading the ABI for your particular processor, which explains how structures are laid out in memory. It's potentially What properties should my fictional HEAT rounds have to punch through heavy armor and ERA? How is sizeof implemented in C? library to work with historical (big) dates and time (eg, 11,043 BC)? How to change background color of Stepper widget to transparent color? WebHere's a trick for finding the size of a variable without using sizeof--not something you'd generally do, but it demonstrates the ability to use pointer arithmetic. How to find sizeof array in C/C++ without using sizeof? Program. I was looking for the answer but didn't find any solutions I liked here. What might be the point in putting a variable exactly in the "STACK" section with __attribute__ ((section("STACK"))? This trick is highly dependent on the layout your compiler uses for stack variables though! To understand this example, you And those are implementation dependent. Copyright 2022 www.appsloveworld.com. Author: Amit Khandelwal 1. csizeof. Counterexamples to differentiation under integral sign, revisited. I would write the following code to find the size of an integer in bytes (assuming no sizeof command and byte = 8 bits): Code: int i = 1; int count = 1; while (i <<= 8) { count++; } //count should contain the size of the integer i in bytes. How to find the address of a string in memory using GDB? why do we need to cast the variable to char * The question is how to do it without using sizeof and we can either be helpful in answering it or not. There may be padding along the fields of a structure. WebC Program to Find the Size of int, float, double and char. thank you for giving example of size of operator for last one week i am looking for this information The sizeof of a structure is not always equal to the sum of sizeof of each individual member. hi this is Gloria Cartwright, Lastly, %d, is for printing ints, use the macros in inttypes.h to print objects like intptr_t or %zu to print the result of the sizeof operator. 34,385. Improve INSERT-per-second performance of SQLite. This is the code: Right method is to allocate an array of structure and compare the memory addresses of consecutive elements of an Array: Note that if we dont convert the address to char* then the answer will always be 1 (because it will talk about the memory block & not memory location). To my mind, this fits into the category of "how do I add two ints without using ++, += or + ?". It's a waste of time. You can try and avoid the mon of that type,And, of To my mind, this fits into the category of "how do I add two ints without using ++, += or + ?". Blog Posts In C++ it is defined as exactly 1 byte (logic inference: sizeof() returns the size of the argument in bytes, sizeof(char)==1 => char is exactly one byte). Now can I find the size of the variable 'i' without sizeof operator? The idea is to use pointer arithmetic ( (& (var)+1)) to determine the offset of the variable, and then subtract the original address of the variable, yielding its size. How to create an array without declaring the size in C? Save my name, email, and website in this browser for the next time I comment. However, I don't really see a valid reason not to use sizeof, but I'm sure you must have one. How to build completely new data type of size n in C or C++ without using any of the user defined data type? disclaimer. Who cares if it'll ruin an interview question? Look, sizeof is the language facility for this. The only one, so it is the only portable way to achieve this. For some special cases you could g if X is datatype: #define SIZEOF(X) (unsigned int)( (X *)0+1 ) ( {x __tmp_x_ [2]; \. Output. Note that I don't declare a variable of type or pointer to X. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Login to Answer. Let us see an example for better understanding: In the above declaration, Integer is the largest structure member (4 bytes) so to prevent the performance penalty compiler inserts some extra padding bytes to improve the performance of the CPU. We make use of First and third party cookies to improve our user experience. This is because of the extra padding byte which inserts by the compiler to avoid alignment issues. WebThen, the size of the char variable is calculated using sizeof() operator. What if a null character is present in the middle of a string? How does sizeof know the size of the operand array? How to link using GCC without -l nor hardcoding path for a library that does not follow the libNAME.so naming convention? In general, using the sizeof operator is a much better idea. Below is the source code for C program to find size of variables using sizeof() operator which is successfully compiled and run on Windows System to produce desired output as shown below : Aboveis the source code for C program to find size of variables using sizeof () operator which is successfully compiled and run on Windows System.The Output of the program is shown above . To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Heres simple program to find size of variables using sizeof() operator in C Programming Language. Is energy "equal" to the curvature of spacetime? Why is Singapore currently considered to be a dictatorial regime and a multi-party democracy by different publications? E.g. how to find out the page size of a processor using C program and malloc? WebC++ Program to Find Size of int, float, double and char in Your System. I would expect that to be rare for an. The possibility of padding prevent all hopes without the knowledge of the rules used for introducing it. #define __SIZE_OF__ (x) \. You can use the following macro, taken from here: #define sizeof_var( var ) C++ Solved programs, problems/Examples with solutions, Write a C Program to find Mean, Variance and Standard deviation of n numbers, C++ Program to find Factorial of a number using class. Calculating the size of structure in c without using the sizeof() operator seems to be difficult but with the help of pointers, we can do it easily. [*] Objects in a very general sense rather than the OOP sense. I know that sizeof is an operator, I have mentioned in the beginning of the article. The compiler is always free to add additional padding anywhere, so there is no 'expected size' - except for sizeof(char), which is defined to be 1. Why is not sizeof for a struct equal to the sum of sizeof of each member in C/C++? To find the size of variable, sizeof operator is How to find the size of structure in C without using sizeof? In C language, sizeof () operator is used to calculate the size of structure, variables, pointers or data types, data types could be pre-defined or user-defined. Using the sizeof () operator we can calculate the size of the structure straightforward to pass it as a parameter. confusion between a half wave and a centre tapped full wave rectifier. Find size of variables using sizeof() operator, Welcome to Coding World | C C++ Java DS Programs, C Program to display sum of even and product of odd numbers, Write a C Program to find the gross salary and net salary, Write a C Program to find the roots of quadratic equation, Write a C program to find HCF of two numbers, Learn Java: An Easy And In-Demand Programming Language. Interview Questions On bitwise Operators C, Interview Questions On Memory Allocation C, Machine Learning, Data Science and Deep Learning, Statistics for Data Science, Data and Business Analysis. Create a pointer to structure and assign the address of the array. Console program does not execute correctly when run from SciTE, C. Segmentation Fault when function modifies dynamically allocated 2d array. Note that char may have more than 8 bits, however Can it really be more than 8 bits in C? Save my name, email, and website in this browser for the next time I comment. Learn more, Find size of array in C/C++ without using sizeof, How to use sizeof() operator to find the size of a data type or a variable in C#, How to swap two numbers without using a temp variable in C#, Swapping two variable value without using third variable in C/C++. After creating the structure, create an array of structures, Here RamInfo[2]. You will get : and from this, the expected size of anything. How to access pointer inside a structure in c. How to use the structure of function pointer in c language? Subtract the pointers to get the size of the structurein c. After creating the structure, create an array of structures, Here sData[2]. What do you mean "of course without using sizeof"? How to swap two arrays without using temporary variable in C language? Do shared libraries use the same heap as the application? So you may be thinking about whether we can only find the size of variables using the sizeof( ) operator. ( (unsigned int) (&__tmp_x_ [1]) - (unsigned int) (&__tmp_x_ [0])); \. }) Surely, you could also just #include
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