﻿ C Program: Convert binary number to octal - w3resource # C Exercises: Convert binary number to octal

## C For Loop: Exercise-53 with Solution

Write a program in C to convert a binary number to octal.

Pictorial Presentation: Sample Solution:

C Code:

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

void main()
{       int n1, n,p=1;
int dec=0,i=1,j,d;
int ocno=0,dn;

printf("\n\nConvert Binary to Octal:\n ");
printf("-------------------------\n");

printf("Input a binary number :");
scanf("%d",&n);
n1=n;
for (j=n;j>0;j=j/10)
{
d = j % 10;
if(i==1)
p=p*1;
else
p=p*2;

dec=dec+(d*p);
i++;
}

/*--------------------------------------------*/
dn=dec;
i=1;

for(j=dec;j>0;j=j/8)
{
ocno=ocno+(j % 8)*i;
i=i*10;
n=n/8;
}

printf("\nThe Binary Number : %d\nThe equivalent Octal  Number : %d \n\n",n1,ocno);
}
```
```

Sample Output:

```Convert Binary to Octal:
-------------------------
Input a binary number :1001

The Binary Number : 1001
The equivalent Octal  Number : 11
```

Flowchart : C Programming Code Editor:

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## C Programming: Tips of the Day

You are seeing the ffffff because char is signed on your system. In C, vararg functions such as printf will promote all integers smaller than int to int. Since char is an integer (8-bit signed integer in your case), your chars are being promoted to int via sign-extension.

Since c0 and 80 have a leading 1-bit (and are negative as an 8-bit integer), they are being sign-extended while the others in your sample don't.

```char    int
c0 -> ffffffc0
80 -> ffffff80
61 -> 00000061
```
Here's a solution:
```char ch = 0xC0;
printf("%x", ch & 0xff);
```

This will mask out the upper bits and keep only the lower 8 bits that you want.

Ref : https://bit.ly/3vOLizM