C PROGRAMMING PROGRAM • POINTERS & DYNAMIC MEMORY

Swap Two Numbers Using Pointers

Learn how to swap two numbers using pointers using a clear C program.

IntermediatePointersAddressPass by reference

PROBLEM UNDERSTANDING

Input and expected output

Sample input

10 25

Sample output

After swapping: 25 10

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

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

int main(void)
{
    int first, second;

    printf("Enter two integers: ");
    scanf("%d %d", &first, &second);
    swap(&first, &second);
    printf("After swapping: %d %d\n", first, second);
    return 0;
}

CURRENT STEP

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SELECTED LINE

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EXPECTED OUTPUT FOR THE SAMPLE

After swapping: 25 10

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Pass variable addresses and modify the original values through dereferenced pointers.
Display the computed result.

Pass variable addresses and modify the original values through dereferenced pointers.

EFFICIENCY

Time and space complexity

Time complexity

O(1)

Auxiliary space

O(1)

DEBUGGING CHECKLIST

Common mistakes

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Use the correct format specifier for every variable.

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Initialize variables before using their values.

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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.