C Program to Convert Binary to Octal

In this article, we will learn how to create a program in C that can convert any given binary number (provided by the user at run-time) into its equivalent octal number. At last, we have also created a function named BinToOct() that does the same job.

But before going through the program, if you are not aware of

then refer to the step-by-step process for binary to octal conversion. Now let's move on to the program.

Binary to octal in C

The question is, "Write a program in C that converts any given binary number into its equivalent octal value." The answer to this question is:

#include<stdio.h>
#include<conio.h>
int main()
{
    int bin, oct=0, i=0, mul=1, count=1, rem, octnum[20];
    printf("Enter any Binary Number: ");
    scanf("%d", &bin);
    while(bin!=0)
    {
        rem = bin%10;
        oct = oct + (rem*mul);
        if(count%3==0)
        {
            octnum[i] = oct;
            mul = 1;
            oct = 0;
            count = 1;
            i++;
        }
        else
        {
            mul = mul*2;
            count++;
        }
        bin = bin/10;
    }
    if(count!=1)
        octnum[i] = oct;
    printf("\nEquivalent Octal Value = ");
    for(i=i; i>=0; i--)
        printf("%d", octnum[i]);
    getch();
    return 0;
}

As the above program was written in the Code::Blocks IDE, here is the first snapshot of the sample run:

c binary to octal conversion

Now supply any binary number, say 1101110, as input and press the ENTER key to see its equivalent octal value as shown in the second snapshot of the sample run given below:

binary to octal conversion in c

Here is the final snapshot of another sample run:

c program convert binary to octal

Program Explained

Binary to Octal in C using a User-Defined Function

The question is, "Write a program in C that converts binary to octal using a user-defined function named BinToOct()." Here we have declared the variable i and the array octnum[20] as global variables (out of both the functions) to make them known inside both the main() and BinToOct() functions.

#include<stdio.h>
#include<conio.h>
void BinToOct(int bin);
int i=0;
int octnum[20];
int main()
{
    int binnum;
    printf("Enter any Binary Number: ");
    scanf("%d", &binnum);
    BinToOct(binnum);
    printf("\nEquivalent Octal Value = ");
    for(i=i; i>=0; i--)
        printf("%d", octnum[i]);
    getch();
    return 0;
}
void BinToOct(int bin)
{
    int oct=0, mul=1, count=1, rem;
    while(bin!=0)
    {
        rem = bin%10;
        oct = oct + (rem*mul);
        if(count%3==0)
        {
            octnum[i] = oct;
            mul = 1;
            oct = 0;
            count = 1;
            i++;
        }
        else
        {
            mul = mul*2;
            count++;
        }
        bin = bin/10;
    }
    if(count!=1)
        octnum[i] = oct;
}

Here is the final snapshot of the above program's sample run:

c binary to octal using function

The same program in different languages

C Quiz


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