Pass by reference in C

Pass by Reference

• Pass by reference in C refers to passing the memory address (i.e., reference) of a variable to a function instead of the value.

• This allows the function to modify the original variable in memory, rather than just working with a copy of the value.

• In C, pass by reference is implemented using pointers. A pointer to a variable is passed to the function, which can then modify the value of the variable by dereferencing the pointer.

Example

Program below demonstrates pass by reference in C:

#include <stdio.h>

// Function that takes a pointer to an int
void increment(int *num)
{
    (*num)++; // dereference the pointer and increment the value
}

int main()
{
    int num = 0;

    printf("num = %d\n", num); // prints "num = 0"

    increment(&num); // pass a pointer to the "num" variable

    printf("num = %d\n", num); // prints "num = 1"

    return 0;
}

Output:

Explanation

• The increment function takes a pointer to an int as an argument.
• Inside the function, the pointer is dereferenced using the * operator, and the value of the variable is incremented.
• When increment(&num) is called in the main function, a pointer to the num variable is passed as an argument.
• The increment function then modifies the value of the num variable in memory, and the updated value is printed in the main function.