# C Program to Convert Binary Number to Decimal and vice-versa

## 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: 110110111
110110111 in binary = 439
```

## Program to convert decimal to binary

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

long long convert(int n){
long long bin = 0;
int rem, i = 1, step = 1;
while (n != 0) {
rem = n % 2;
printf("Step %d: %d/2, Remainder = %d, Quotient = %dn", step++, n, rem, n / 2);
n /= 2;
bin += rem * i;
i *= 10;
}
return bin;
}
``````

Output

```Enter a decimal number: 19
Step 1: 19/2, Remainder = 1, Quotient = 9
Step 2: 9/2, Remainder = 1, Quotient = 4
Step 3: 4/2, Remainder = 0, Quotient = 2
Step 4: 2/2, Remainder = 0, Quotient = 1
Step 5: 1/2, Remainder = 1, Quotient = 0
19 in decimal = 10011 in binary```

## C Example for Beginners: C Program to Convert Binary Number to Decimal and vice-versa

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