Guest Article Try this: int a; 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). I think that parentheses is good for the readability and there is no side effect for parentheses. WebThen, the size of the char variable is calculated using sizeof() operator. I am trying to find the size Japanese girlfriend visiting me in Canada - questions at border control? . How do I determine the size of my array in C? Next in this series: how to obtain the address-of without using an ampersand. 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. int x; x = sizeof (int); To get the size of a variable, without using the sizeof, try the following code . By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Author: Amit Khandelwal 1. Login to Answer. Connect and share knowledge within a single location that is structured and easy to search. What properties should my fictional HEAT rounds have to punch through heavy armor and ERA? How to pass a constant array literal to a function that takes a pointer without using a variable C/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. Look, sizeof is the language facility for this. 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++. thank you for giving example of size of operator for last one week i am looking for this information 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. The usage of sizeof is simple. Here firstly, we calculate the size of the whole array or calculate the memory it is taking up. Get the address of the first element using the sData[0] and sData[1]. Variable-size data is data whose size is not known at compile time or whose size can change at run time. Data Structure Alignment : Linker or Compiler. Counterexamples to differentiation under integral sign, revisited. When can I find out more? 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 invalid application of 'sizeof' to incomplete type 'struct array[]', How to find the size of a variable without using sizeof. So the size of the InfoData will be 12 bytes due to the padding bytes. Why is not sizeof for a struct equal to the sum of sizeof of each member in C/C++? Blog Posts I have tried this method, but i am getting a warning .. When adding multiple answers to a question, please include an explanation to them which explains the difference. Making statements based on opinion; back them up with references or personal experience. How to swap two numbers without using the third or a temporary variable using C Programming? Using flutter mobile packages in flutter web. How to find the size of an int[] in C/C++? Switch statement with huge number of cases, Delete the last integer in an array without it becoming zero, Use poll() to check for file modification, How to extract a negative number from a string, How would you define a simple "min" method in obj-c. In C language, sizeof() operator is used to calculate the size of. How to link using GCC without -l nor hardcoding path for a library that does not follow the libNAME.so naming convention? To my mind, this fits into the category of "how do I add two ints without using ++, += or + ?". 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. @Paul: I understand that you are insisting on being safe and being dependent on compiler. TabBar and TabView without Scaffold and with fixed Widget. But here I am interested in calculating the size of structure in C without using the sizeof() operator. @2501 Padding perhaps. 5. Follow-up question: I want to include a header file I wrote, without using any preprocessor directives, of course. Why does it matter if this person should use something or not? How will you find the size of a structure in C/C++ language without using sizeof operator. whenComplete() method not working as expected - Flutter Async, iOS app crashes when opening image gallery using image_picker. When should i use streams vs just accessing the cloud firestore once in flutter? 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'). What if a null character is present in the middle of a string? The C-FAQ claims that there do exist such machines. E.g. Using the sizeof() operator we can calculate the size of the structure straightforward to pass it as a parameter. You will receive mail with link to set new password. After creating the structure, create an array of structures, Here RamInfo[2]. To understand this example, you #define __SIZE_OF__ (x) \. 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. It is also an important interview question that is generally asked by the interviewer to check the understanding of pointer. More tips. 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. How to find the size of a variable without using sizeof. Asking for help, clarification, or responding to other answers. 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. sizeof (int) [required] sizeof foo_variable [not required]. 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. So, by exploiting this fact I came up with following: For the following user-defined datatype. You can use the following macro, taken from here: #define sizeof_var( var ) Note that I don't declare a variable of type or pointer to X. #include struct ((I'm keeping my comment so that others dont ask the same question, or don't apply the same technique directly in C++, as C++'s type-system is a bit more complex)). Is MethodChannel buffering messages until the other side is "connected"? confusion between a half wave and a centre tapped full wave rectifier. Who cares if it'll ruin an interview question? WebC++ Program to Find Size of int, float, double and char in Your System. WebHere is how to find size of a structure without sizeof operator. See, Method-1 in solution). hi this is Gloria Cartwright, In C programming language you can check the size of a variable using sizeof operator. 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. Why of course? @KeithThompson: Oops yes! ( (unsigned int) (&__tmp_x_ [1]) - (unsigned int) (&__tmp_x_ [0])); \. }) How does this piece of code determine array size without using sizeof( )? Swapping two variables without using third variable, Find minimum cost to travel to the destination, Find kth largest element in running stream of numbers. [*] Objects in a very general sense rather than the OOP sense. There may be padding along the fields of a structure. - Aticleworld. - AticleWorld, 8 Tips to Increase the Performance of Your "C" Code. 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. It is a compile-time execution operator. While 0 is guaranteed to mean "null pointer" in all implementations, it doesn't have to be represented internally by address 0, in which case this will fail. 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. 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. How to find sizeof array in C/C++ without using sizeof? Create a pointer to structure and assign the NULL pointer. 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). 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). No. Explanation: By using the &x, we get the base address of the variable x and by adding 1 to it we get the base address of next short int type. It's a waste of time. Your email address will not be published. Also sizeof is an operator and does not require parentheses unless operating on a type. 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. Then the size of the char array is find by dividing the size of the complete array by the size of the first variable. How do I arrange multiple quotations (each with multiple lines) vertically (with a line through the center) so that they're side-by-side? To get the size of a variable, without using the sizeof, try the following code , Enjoy unlimited access on 5500+ Hand Picked Quality Video Courses. Subtract both addresses to get the size of the structure. I know that sizeof is an operator, I have mentioned in the beginning of the article. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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 get the width/height of jpeg file without using library? C. Aricent. By creating foo[2], I will now have 2 consecutive foo objects in memory. Get the base address of the variable 'Var' using address of(&) operator. By omitting the parens you tell the reader that this is an object, not a type. How to create an array without declaring the size in C? 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. 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. clone system call's argument stores in stack or somewhere else? To get the size of a variable, sizeof is used. The possibility of padding prevent all hopes without the knowledge of the rules used for introducing it. And those are implementation dependent. How to find the address of a string in memory using GDB? Write a C program to find size of variables using sizeof() operator. The only one, so it is the only portable way to achieve this. For example, if you have Well, I am an amateur..but I tried out this problem and I got the right answer without using sizeof. Hope this helps.. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. How can you find the size of a datatype without creating a variable or pointer, or using sizeof of the datatype? 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. How to find size of a variable without using sizeof operator How to share internet from mobile to PC without hotspot? Find centralized, trusted content and collaborate around the technologies you use most. How do you find the size of a variable disclaimer. I believe this interview question is intended to ask you to think outside the box. It uses a pointer which is not valid according to the question. The question is how to do it without using sizeof and we can either be helpful in answering it or not. You could puzzle it out by reading the ABI for your particular processor, which explains how structures are laid out in memory. Well, I am an amateur..but I tried out this problem and I got the right answer without using sizeof. Is energy "equal" to the curvature of spacetime? How to build completely new data type of size n in C or C++ without using any of the user defined data type? Implement your own sizeof operator using C++. // without using Using the sizeof( ) Operator. A Computer Science portal for geeks. Copyright 2016-2020 CodezClub.com All Rights Reserved. What do you mean "of course without using sizeof"? Stay tuned! Now can I find the size of the variable 'i' without sizeof operator? Are defenders behind an arrow slit attackable? Would love your thoughts, please comment. How would you create a standalone widget from this widget tree? 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 WebWhat does variable in size mean? WebC program to print size of variables using sizeof() operator. 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. 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). See my answer. Save my name, email, and website in this browser for the next time I comment. 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. int a,int b char *p1,*p2; p1= (char*)a; p2= (char*)b; p1-p2. How can one print a size_t variable portably using the printf family? Is there a higher analog of "category with all same side inverses is a groupoid"? affiliate-disclosure Using the sizeof() operator we can calculate the size of the structure straightforward to pass it as a parameter. How can I do that? document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); About 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. The sizeof( ) operator can be used to find the size of data types and expressions. For example: struct Student{ int rollno; char name[25]; Your email address will not be published. Which is better USB tethering or Mobile hotspot? 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 Why isn't sizeof for a struct equal to the sum of sizeof of each member in C/C++? The second most important use case for this operator is allocating a dynamic memory, so we use the sizeof operator when allotting the space. How to find the size of a variable without using sizeof. ( {x __tmp_x_ [2]; \. We can find the size of an array Max Distance between two occurrences of the same element. (Note: sum of sizes of all fields of a structure may not be equal to the exact memory allocated to the structure. @Charles Balley this question is asked in Cisco interviews. Does http_proxy automatically work in Linux for all applications? Required fields are marked *. Agree - AticleWorld, What is importance of struct hack in c? 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. In this example, you will learn to evaluate the size of each variable using sizeof operator. NOTE: Simply consider that 'i' is declared and dont bother if it is an int or char or float or double datatype. 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. 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). Output. Assuming did my pointer arithmetic correctly, this should be the ticket - and its portable! Why is Singapore currently considered to be a dictatorial regime and a multi-party democracy by different publications? 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 Greedy Solution to Activity Selection Problem. create an array of structures, Here aiData[2]. 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. How can I move to a pointer position directly without using the ++ operator? 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. Is this possible? In general, using the sizeof operator is a much better idea. For example: We are using sizeof operator to calculate the sizeof fields.. . How to swap two arrays without using temporary variable in C language? The question asks how to do this "without declaring a variable or pointer of that type.", There are multiple issues with that answer. In this article, I will describe some methods to calculate the size of the structure in c without using the sizeof the operator. of that type,And, of All rights reserved. WebYou may be tempted to calculate the size of all the fields of structure, then compute the sum of all these sizes and get the result. So here we will use this technique to calculate the size of a structure. You can directly pass a type like: sizeof (int); . sizeof() is an operator in c programming language, which is used to get the occupied size by the variable or value. How is the size of a variable length array computed at runtime in C99? Why do some airports shuffle connecting passengers through security again. How is sizeof implemented in C? What might be the point in putting a variable exactly in the "STACK" section with __attribute__ ((section("STACK"))? Improve INSERT-per-second performance of SQLite. why do we need to cast the variable to char * Please enter your email address. sizeof(int); For double datatype Why isn't sizeof for a struct equal to the sum of sizeof of each member? Then we divide that number with the sizeof of the data type; in this program, it is int. What does sizeof (function(argument)) return? Lets say you need to find the size of int datatype . document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); document.getElementById( "ak_js_2" ).setAttribute( "value", ( new Date() ).getTime() ); This post is priceless. The sizeof of a structure is not always equal to the sum of sizeof of each individual member. To find the size of variable, sizeof operator is How can you find the size of a datatype without creating a variable or pointer, or using sizeof of the datatype? Code Explanation. 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. (adsbygoogle = window.adsbygoogle || []).push({}); When doing pointer math I like to cast the pointers to intptr_t or uintptr_t not char*. This is because of the extra padding byte which inserts by the compiler to avoid alignment issues. In order to use sizeof the zoperator, you can pass variable to the operator. To use the sizeof(), we can take the value using a variable x, using &x, it will print the address of it. How to change the stack size using ulimit or per process on Mac OS X for a C or Ruby program? I was looking for the answer but didn't find any solutions I liked here. Example: sizeof (var1); sizeof is not a function. How does sizeof know the size of the operand array? How to copy local variable to global variable if both have the same names in C without using a third variable? C/C++ add input to stdin from the program? Note: This code uses "%zu" which requires C99 onward. 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? Can we keep alcoholic beverages indefinitely? A lot of these answers are assuming you know what your structure will look like. 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. I am a professional blogger, present started writing artilces on job description template, Your email address will not be published. You can try and avoid the monsters of undefined behaviour by doing something like this. We can also calculate the size of the structure using the pointer subtraction. library to work with historical (big) dates and time (eg, 11,043 BC)? Console program does not execute correctly when run from SciTE, C. Segmentation Fault when function modifies dynamically allocated 2d array. How to change background color of Stepper widget to transparent color? I will make a better assumption saying. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Ready to optimize your JavaScript with Rust? Lost your password? I mean how about writing our own sizeof operator. 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. This is the code: You may be tempted to calculate the size of all the fields of structure, then compute the sum of all these sizes and get the result. So you may be thinking about whether we can only find the size of variables using the sizeof( ) operator. Why was USB 1.0 incredibly slow even for its time? Required fields are marked *. 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. Here we need to use some techniques to calculate the size of the structure in C. I am describing this technique, using a few examples. 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. Solution 1. By using this website, you agree with our Cookies Policy. why cant we just subtarct like piData2 piData1, You should read this article, https://aticleworld.com/pointer-arithmetic/, Your email address will not be published. One simple way of doing this would be using arrays. WebFind size of variables using sizeof () operator. Thanks mark for the suggestion. To learn more, see our tips on writing great answers. I am trying to find the size of an integer. Do shared libraries use the same heap as the application? Being a riddle, you have to find an unusual, and possibly absurd, method to do it. If you could at least allocate space for the variable, and fill some sentinel value into it, you could change it bit by bit, and see if the value changes, but this still would not tell you any information about padding. 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. rev2022.12.11.43106. Why do quantum objects slow down when volume increases? It is also an important interview question that is generally asked by the interviewer to check the. (If a field is stored in two words of memory then it will take 2 reads, but if we leave the space in between so that the field is stored in just one word, the read & write operation will take only one cycle, read more about it here). How to find the position of the only-set-bit in a 64-bit value using bit manipulation efficiently? The possibility of padding prevent all hopes without the knowledge of the rules used for introducing it. Affordable solution to train a team and make them project ready. This program declares 4 variables of type int, float, double and char. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive programming/company interview Questions. Csharp Programming Server Side Programming. To get the size of a variable, sizeof is used. int x; x = sizeof (int); To get the size of a variable, without using the sizeof, try the following code . // without using sizeof byte [] dataBytes = BitConverter.GetBytes (x); int d = dataBytes.Length; Here is the complete code. //don't try to do this with doubles. What is the size of operator? This should give you the size of your variable, Program to find Size of the variable without using sizeof operator, I hope that below code would solve your problem in c++ without using sizeof() operator, for any variables like (int, char, float, double, char, short and many more). 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