C Program to Convert Octal to Binary

In this tutorial, we will write a C program to convert an octal number into binary using a while loop. Before that, you must have knowledge of the following topics in C.

• C operator
• C while loop

Binary number

The binary numbers are based on 0 and 1, so it is a base 2 number. They are the combination of 0 and 1. For example, 1001, 110101, etc.

Octal number

The octal numbers are the numbers with base 8 and use the digits 0 to 7. Example: 8 in decimal is represented as 10 in octal, 25 as 31, and so on.

Example:

Input: 51
Output: 101001

Let us go through a program for the Octal to Binary Conversion in C.

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C Program to Convert Octal to Binary

Source code: convert octal number to binary number using function

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

int conversionFunc(int octalNum)
{
  int decNum = 0, i = 0;
  int binaryNum = 0;

  while (octalNum != 0)
  {
    decNum += (octalNum % 10) *pow(8, i);
    ++i;
    octalNum /= 10;
  }

  i = 1;

  while (decNum != 0)
  {
    binaryNum += (decNum % 2) *i;
    decNum = decNum / 2;
    i *= 10;
  }

  return binaryNum;
}

int main()
{
  int octalNum;

  printf("Enter an octal number: ");
  scanf("%d", &octalNum);

  printf("Equivalent Binary Value: %d", conversionFunc(octalNum));

  return 0;
}

Output:

Enter an octal number: 51
Octal Binary Value: 101001

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