Example
Input
Input octal number: 172
Output
Decimal number: 122
Logic to convert from octal to decimal
/**
* C program to convert Octal number system to Decimal number system
*/
#include <stdio.h>
#include <math.h>
int main()
{
long long octal, tempOctal, decimal;
int rem, place;
/* Input octal number from user */
printf("Enter any octal number: ");
scanf("%lld", &octal);
tempOctal = octal;
decimal = 0;
place = 0;
/*
* Convert octal to decimal
*/
while(tempOctal > 0)
{
/* Extract the last digit of octal */
rem = tempOctal % 10;
/* Convert last octal digit to decimal */
decimal += pow(8, place) * rem;
/* Remove the last octal digit */
tempOctal /= 10;
place++;
}
printf("Octal number = %lld\n", octal);
printf("Decimal number = %lld", decimal);
return 0;
}
/*
Output :
Enter any octal number: 172
Octal number = 172
Decimal number = 122
*/