2진수 10진수 변환

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

int convertBinaryToOctal(long long binaryNumber);
int main(void){
long long binaryNumber;

printf("Enter a binary number: ");
scanf("%lld", &binaryNumber);

printf("%lld in binary = %d in octal\n", binaryNumber, convertBinaryToOctal(binaryNumber));
return 0;
}

int convertBinaryToOctal(long long binaryNumber){
int octalNumber = 0, decimalNumber = 0, i = 0;

while(binaryNumber != 0){
decimalNumber += (binaryNumber%10) * pow(2,i);
++i;
binaryNumber /= 10;
}

i = 1;

while(decimalNumber != 0){
octalNumber += (decimalNumber %8) * i;
decimalNumber /= 8;
i *= 10;
}

return octalNumber;
}

이진수 입력 : 101001
8 진수로 51