C programming, Transform octal numbers into decimal format and convert them back to octal.

#include <stdio.h>

#include <math.h>

int convertDecimalToOctal(int decimalNumber);

int main() {

    int decimalNumber;

    printf("Enter a decimal number: ");

    scanf("%d", &decimalNumber);

    printf("%d in decimal = %d in octal", decimalNumber, convertDecimalToOctal(decimalNumber));

    return 0;

}

int convertDecimalToOctal(int decimalNumber) {

    int octalNumber = 0, i = 1;

    while (decimalNumber != 0) {

        octalNumber += (decimalNumber % 8) * i;

        decimalNumber /= 8;

        i *= 10;

    }

    return octalNumber;

}