Passing Arguments by Value and Address

1.) Passing Arguments by Value:

Passing arguments by value means the function receives a copy of the actual value passed to it. Any modifications made to the parameter inside the function do not affect the original variable.

Key Features:

• The original variable remains unchanged.
• Safe from unintended modifications.
• Used when you don’t need to modify the original data.

Example:

#include <stdio.h>

void modify(int x) {
    x = x + 10;
    printf("Inside function: x = %d\n", x);
}

int main() {
    int a = 5;
    modify(a);
    printf("Outside function: a = %d\n", a); // Value remains 5
    return 0;
}

Output:

Inside function: x = 15
Outside function: a = 5

2.) Passing Arguments by Address (Pass by Reference):

Passing arguments by address (also called pass by reference) means passing the memory address of the variable to the function.

• Any changes made to the parameter inside the function directly modify the original variable.

Key Features:

• The original variable can be changed.
• Used when a function needs to modify the original data.
• Achieved using pointers in C.

Example:

#include <stdio.h>

void modify(int *x) {
    *x = *x + 10;
    printf("Inside function: x = %d\n", *x);
}

int main() {
    int a = 5;
    modify(&a);
    printf("Outside function: a = %d\n", a); // Value becomes 15
    return 0;
}

Output:

Inside function: x = 15
Outside function: a = 15