# C Program to Convert Binary Number to Decimal Number System

• Write a C program to convert binary number to decimal number system.
• Wap in C to convert a base 2 number to a base 10 number.

#### Required Knowledge

This program converts a binary number( base 2) to decimal number (base 10). Binary number system is a base 2 number system using digits 0 and 1 whereas Decimal number system is base 10 and using digits from 0 to 9. Given a binary number as input from user convert it to decimal number.

##### For Example
00000111 in Binary is equivalent to 7 in Decimal number system.

Algorithm to convert Binary to Decimal number
• We multiply each binary digit with 2i and add them, where i is the position of the binary digit(starting from 0) from right side. Least significant digit is at position 0.
Let's convert 0101 binary number to decimal number
Decimal number = 0*23 + 1*22 + 0*21 + 1*20 = 0 + 4 + 0 + 1 = 5

## C program to convert a decimal number to octal number

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

int main() {
long binaryNumber, decimalNumber=0;
int position=0, digit;

printf("Enter a Binary Number\n");
scanf("%ld", &binaryNumber);

while(binaryNumber!=0) {
/* get the least significant digit of binary number */

digit = binaryNumber%10;
decimalNumber += digit*pow(2, position);

position++;
binaryNumber /= 10;
}

printf("Decimal Number : %ld", decimalNumber);

return 0;
}
```
Program Output
```Enter a Binary Number
00000111
Decimal Number : 7
```
```Enter a Binary Number
00010000
Decimal Number : 16
```

Related Topics