C Exercises: Reverse digits of a given a 32-bit signed integer

Last update on August 09 2025 12:47:06 (UTC/GMT +8 hours)

5. Reverse 32-bit Signed Integer Variants

Write a C program to reverse the digits of a 32-bit signed integer.

C Code:

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>

static int reverse(int x)
{
    int y = 0;
    while (x != 0) {
        int n = x % 10;
        if (y > INT_MAX / 10 || y < INT_MIN / 10) {
            return 0;
        }
        y = y * 10 + n;
        x /= 10;
    }
    return y;
}
int main(void)
{
    int x = 123;
    printf("Original integer: %12d",x);
    printf("\nReverse integer : %12d",reverse(x));
    return 0;
}

Sample Output:

Original integer:          123
Reverse integer :          321

Pictorial Presentation:

C Programming: Reverse digits of a given a 32-bit signed integer.

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to reverse a 32-bit signed integer while returning 0 if the result overflows.
Write a C program to reverse an integer using recursion without converting it to a string.
Write a C program to reverse the digits of a 32-bit integer using arithmetic operations only.
Write a C program to reverse a negative 32-bit integer and preserve its sign correctly.

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