C Programming Code Examples C > Conversions Code Examples Program to Convert Octal to Decimal Program to Convert Octal to Decimal C Program to Convert Octal Number to Decimal and vice-versa #include <stdio.h> #include <math.h> long long convertOctalToDecimal(int octalNumber); int main() { int octalNumber; printf("Enter an octal number: "); scanf("%d", &octalNumber); printf("%d in octal = %lld in decimal", octalNumber, convertOctalToDecimal(octalNumber)); return 0; } long long convertOctalToDecimal(int octalNumber) { int decimalNumber = 0, j = 0; while(octalNumber != 0) { decimalNumber += (octalNumber%10) * pow(8,j); ++j; octalNumber/=10; } j = 1; return decimalNumber; }