# Binary to Decimal Number Conversion

Binary to Decimal Number Conversion” is one of the classic programming problem exercise. Here, we are given a binary number, entered by user and our task is to write a program to  convert the given binary number to its equivalent decimal number.

Example:

```INPUT:
Binary = 111
OUTPUT:
Decimal = 7
INPUT:
Binary = 100
OUTPUT:
Decimal = 4```

To convert binary number into decimal, we will scan the number from right to left and put it into formula.

```FORMULA TO CONVERT BINARY TO DECIMAL:
2^0 * (last digit) + 2^1 * (second last digit) + ….```

C++ Program to convert binary to decimal is as follows:

```#include<bits/stdc++.h>
using namespace std;
long int convert(long int);
int main()
{
// Scan the binary number
long int binary;
cout<<"Enter the binary number : ";
cin>>binary;

//Call the convert function
long int decimal = convert(binary);

//Printing the decimal equivalent
cout<<"The decimal equivalent of "<<binary<<" is "<<decimal;
}
long int convert(long int binary)
{
long int res = 0;
int i = 0;
while(binary > 0)
{
int digit = binary % 10; /* Extracting the last digit */
res = res + (digit * pow(2,i)); /* Putting it into formula */
binary =  binary/10;
i++;
}
return res;
}
```
```OUTPUT:
Enter the binary number : 111
The decimal equivalent of 111 is 7```

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