C Program For Convert Binary Number to Decimal or Decimal Number to Binary Using Function

#include <stdio.h>
#include <math.h>
int bin_to_dec(int n);
int dec_to_bin(int n);
int main()
{
   int n;
   char c;
   printf("Instructions:\n");
   printf("1. Enter alphabet 'd' to convert binary to decimal.\n");
   printf("2. Enter alphabet 'b' to convert decimal to binary.\n");
   scanf("%c",&c);
   if (c =='d' || c == 'D')
   {
       printf("Enter a binary number: ");
       scanf("%d", &n);
       printf("%d in binary = %d in decimal", n, bin_to_dec(n));
   }
   if (c =='b' || c == 'B')
   {
       printf("Enter a decimal number: ");
       scanf("%d", &n);
       printf("%d in decimal = %d in binary", n, dec_to_bin(n));
   }
   return 0;
}

int dec_to_bin(int n)  /* Function to convert decimal to binary.*/
{
    int rem, i=1, binary=0;
    while (n!=0)
    {
        rem=n%2;
        n/=2;
        binary+=rem*i;
        i*=10;
    }
    return binary;
}

int bin_to_dec(int n) /* Function to convert binary to decimal.*/

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

Output:

Instructions:

1. Enter alphabet 'd' to convert binary to decimal.

2. Enter alphabet 'b' to convert decimal to binary.

d

Enter a binary number: 110101001

110101001 in binary = 425 in decimal