﻿ C : Convert binary number into a decimal using math function # C Exercises: Convert a binary number into a decimal using math function

## C For Loop: Exercise-46 with Solution

Write a program in C to convert a binary number into a decimal number using math function.

Pictorial Presentation: Sample Solution:

C Code:

``````#include <stdio.h>
#include <math.h>
void main()
{       int n1, n;
int dec=0,i=0,j,d;

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

printf("Input  the binary number :");
scanf("%d",&n);
n1=n;
while(n!=0)
{  d = n % 10;
dec=dec+d*pow(2,i);
n=n/10;
i++;
}
printf("\nThe Binary Number : %d\nThe equivalent Decimal  Number is : %d\n\n",n1,dec);
}
```
```

Sample Output:

```Convert Binary to Decimal:
-------------------------
Input  the binary number :1010100

The Binary Number : 1010100
The equivalent Decimal  Number is : 84
```

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