# C Program to Convert Binary to Decimal Number

Binary to Decimal conversion in C: We can convert any binary number(base-2 (0 or 1)) into decimal number (base-10 (0 to 9))   by c program.

Decimal Number

Decimal number is a base 10 number because it ranges from 0 to 9, there are total 10 digits between 0 to 9. Any combination of digits is decimal number such as 23, 445, 132, 0, 2 etc.

Binary Number

Binary number is a base 2 number because it is either 0 or 1. Any combination of 0 and 1 is binary number such as 1001, 101, 11111, 101010 etc.

To understand this example, you should have the knowledge of the following C programming topics:

C Functions
C User-defined functions

```/*Program to convert binary to decimal*/

#include <math.h>
#include <stdio.h>
int convert(long long n);
int main() {
long long n;
printf("Enter a binary number: ");
scanf("%lld", &n);
printf("%lld in binary = %d in decimal", n, convert(n));
return 0;
}

int convert(long long n) {
int dec = 0, i = 0, rem;
while (n != 0) {
rem = n % 10;
n /= 10;
dec += rem * pow(2, i);
++i;
}
return dec;
}```

Output

Enter a binary number: 1001
1001 in binary = 9 in decimal

Enter a binary number: 110011
110011 in binary = 51 in decimal

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