C PROGRAMMING PROGRAM • FUNCTIONS, PREPROCESSOR & COMMAND LINE

Simulate Call by Reference Using Pointers

Learn how to simulate call by reference using pointers using a clear C program.

BeginnerPointer parametersAddress operatorDereference

PROBLEM UNDERSTANDING

Input and expected output

Sample input

No input required

Sample output

After call: 20 10

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

void swap_values(int *first, int *second)
{
    int temporary = *first;
    *first = *second;
    *second = temporary;
}

int main(void)
{
    int first = 10, second = 20;
    swap_values(&first, &second);
    printf("After call: %d %d\n", first, second);
    return 0;
}

CURRENT STEP

Select Start to walk through the important lines.

SELECTED LINE

No line selected

EXPECTED OUTPUT FOR THE SAMPLE

After call: 20 10

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Pass variable addresses so the function can modify the original values through dereferencing.
Display the computed result.

Pass variable addresses so the function can modify the original values through dereferencing.

EFFICIENCY

Time and space complexity

Time complexity

O(1)

Auxiliary space

O(1)

DEBUGGING CHECKLIST

Common mistakes

Check this

Use the correct format specifier for every variable.

Check this

Initialize variables before using their values.

Check this

Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.