program:
#include <math.h>
#include <stdio.h>
long long convert(int oct);
int main() {
int oct;
printf("Enter an octal number: ");
scanf("%d", &oct);
printf("%d in octal = %lld in binary", oct, convert(oct));
return 0;
}
long long convert(int oct) {
int dec = 0, i = 0;
long long bin = 0;
// converting octal to decimal
while (oct != 0) {
dec += (oct % 10) * pow(8, i);
++i;
oct /= 10;
}
i = 1;
// converting decimal to binary
while (dec != 0) {
bin += (dec % 2) * i;
dec /= 2;
i *= 10;
}
return bin;
}
output: