Differentiate between call by value and call by reference with a suitable example.

In call by value the function receives copies of the arguments, so changes inside the function do not affect the caller. In call by reference the function receives the addresses of the arguments (pointers), so it can change the caller's variables.

#include <stdio.h>
void byValue(int x) { x = 100; }
void byRef(int *x)  { *x = 100; }

int main(void) {
    int a = 5, b = 5;
    byValue(a);   /* a is still 5 */
    byRef(&b);    /* b is now 100 */
    printf("a = %d, b = %d\n", a, b);
    return 0;
}

Output: a = 5, b = 100.