Sizeof Operator in C Programming Language

Lets write a C program to see how to use sizeof() method or function in C programming language.

sizeof() is a builtin method/function present in C programming. It is used to calculate the size(in bytes) that a datatype occupies in the computers memory.

sizeof() method takes a single argument and it is not a function whose value is determined at run time, but rather an operator whose value is determined by compiler – so it’s called as compile time unary operator.

sizeof() method can be used with primitive data type like int, float, char or user defined data types like structures, unions etc.

Video Tutorial: Sizeof Operator in C Programming Language

Source Code: Sizeof Operator in C Programming Language

#include < stdio.h >

int main()
{
    int a, a1[10];
    char s;
    char s1[10];
    int b = 10, c = 5;

    printf("Size of a single character is %d byes\n", sizeof(s));
    printf("Size of a character array s1[10] is %d byes\n", sizeof(s1));
    printf("Size of a integer is %d byes\n", sizeof(a));
    printf("Size of a long integer is %d byes\n", sizeof(long int));
    printf("Size of a long long integer is %d byes\n", sizeof(long long int));
    printf("Size of a integer array a1[10] is %d byes\n", sizeof(a1));
    printf("Size of a float is %d byes\n", sizeof(float));
    printf("Size of a double is %d byes\n", sizeof(double));
    printf("Size of a long double is %d byes\n", sizeof(long double));
    printf("Size of a b+c is %d byes\n", sizeof(b+c));

    return 0;
}

Output:
Size of a single character is 1 byes
Size of a character array s1[10] is 10 byes
Size of a integer is 4 byes
Size of a long integer is 4 byes
Size of a long long integer is 8 byes
Size of a integer array a1[10] is 40 byes
Size of a float is 4 byes
Size of a double is 8 byes
Size of a long double is 12 byes
Size of a b+c is 4 byes

short, int, long int, long long int

#include < stdio.h >

int main()
{
    printf("Size of short data type is %d\n", sizeof(short));
    printf("Size of integer data type is %d\n", sizeof(int));
    printf("Size of long integer data type is %d\n", sizeof(long int));
    printf("Size of long long integer data type is %d\n", sizeof(long long int));

    return 0;
}

Output:
Size of short data type is 2
Size of integer data type is 4
Size of long integer data type is 4
Size of long long integer data type is 8

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