Question

How to reverse a number using recursion in C

Answer 1

#include <stdio.h>
#include <math.h>

int reverse_recursion(int n, int len) {
    if (len == 1) {
        return n;
    }
    else {
        return (((n % 10) * pow(10, len - 1)) + reverse_recursion(n / 10, --len));
    }
}

int main(void) {
    int n = 1859, len = 0;

    int tmp = n;
    while (tmp != 0) {
        len++;
        tmp = tmp / 10;
    }

    printf("%d\n", reverse_recursion(n, len));

    return 0;
}




/*
run:

9581

*/

 

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