sizeof operator in C
It is used to find the size(in bytes) of data type or variable. Consider the following examples,
Example 1:
int arr[100];
sizeof(int) - 4 bytes // size of an integer
sizeof(arr) - 400 bytes // size of 100 elements in an integer array
Example 2:
Structure is a user defined compound data type which can have elements of different data types grouped under a common name. We will see more about structures in forth coming tutorials.
struct student {
char name[100];
int age, rollno;
};
struct student obj, *ptr
sizeof(struct student) - 108 bytes // size of structure student
sizeof(obj) - 108 bytes // size of structure variable of type student
sizeof(ptr) - 4 bytes // size of pointer to structure of type student
The total size of the structure student is 108 bytes(name - 100 bytes, age - 4 bytes, rollno - 4 bytes). Here, obj is a structure variable of type student and ptr is a pointer to structure of type student.
The return type of sizeof() operator is unsigned integer. And this operator is defined in <stddef.h>
Example C program on sizeof() operator
Example 1:
int arr[100];
sizeof(int) - 4 bytes // size of an integer
sizeof(arr) - 400 bytes // size of 100 elements in an integer array
Example 2:
Structure is a user defined compound data type which can have elements of different data types grouped under a common name. We will see more about structures in forth coming tutorials.
struct student {
char name[100];
int age, rollno;
};
struct student obj, *ptr
sizeof(struct student) - 108 bytes // size of structure student
sizeof(obj) - 108 bytes // size of structure variable of type student
sizeof(ptr) - 4 bytes // size of pointer to structure of type student
The total size of the structure student is 108 bytes(name - 100 bytes, age - 4 bytes, rollno - 4 bytes). Here, obj is a structure variable of type student and ptr is a pointer to structure of type student.
The return type of sizeof() operator is unsigned integer. And this operator is defined in <stddef.h>
Example C program on sizeof() operator
#include <stdio.h>
struct student {
char name[100];
int age, rollno;
};
int main() {
int arr[100];
struct student obj, *ptr;
printf("sizeof(int): %d\n", sizeof(int)); // size of integer
printf("sizeof(arr): %d\n", sizeof(arr)); // sizeof array
printf("sizeof(struct student): %d\n",
sizeof(struct student)); // size of structure
printf("sizeof(obj): %d\n", sizeof(obj)); // obj is of type struct student
printf("sizeof(ptr): %d\n", sizeof(ptr)); // ptr is pointer to struct student
return 0;
}
Output:
jp@jp-VirtualBox:~/$ ./a.out
sizeof(int): 4
sizeof(arr): 400
sizeof(struct student): 108
sizeof(obj): 108
sizeof(ptr): 4
sizeof(int): 4
sizeof(arr): 400
sizeof(struct student): 108
sizeof(obj): 108
sizeof(ptr): 4
sizeof operator in C
Reviewed by Mursal Zheker
on
Minggu, Desember 29, 2013
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