###### C++ Functions

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

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

In this example, we will learn to convert binary number to decimal, and decimal number to binary manually by creating user-defined functions.

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

## convert binary number to decimal

Visit this page to learn how to convert binary number to decimal.

## Example 1: Program to convert binary number to decimal

``````#include <iostream>
#include <cmath>
using namespace std;
int convertBinaryToDecimal(long long);

int main()
{
long long n;

cout << "Enter a binary number: ";
cin >> n;

cout << n << " in binary = " << convertBinaryToDecimal(n) << "in decimal";
return 0;
}

int convertBinaryToDecimal(long long n)
{
int decimalNumber = 0, i = 0, remainder;
while (n!=0)
{
remainder = n%10;
n /= 10;
decimalNumber += remainder*pow(2,i);
++i;
}
return decimalNumber;
}``````

Output 1

```Enter a binary number: 1111
1111 in binary = 15```

## Convert decimal number to binary

Visit this page to learn, how to convert decimal number to binary.

## Example 2: Program to Convert decimal number to binary

``````#include <iostream>
#include <cmath>
using namespace std;
long long convertDecimalToBinary(int);

int main()
{
int n, binaryNumber;

cout << "Enter a decimal number: ";
cin >> n;
binaryNumber = convertDecimalToBinary(n);
cout << n << " in decimal = " << binaryNumber << " in binary" << endl ;
return 0;
}

long long convertDecimalToBinary(int n)
{
long long binaryNumber = 0;
int remainder, i = 1, step = 1;

while (n!=0)
{
remainder = n%2;
cout << "Step " << step++ << ": " << n << "/2, Remainder = "
<< remainder << ", Quotient = " << n/2 << endl;

n /= 2;
binaryNumber += remainder*i;
i *= 10;
}
return binaryNumber;
}``````

Output 1

```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```

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We hope that this Example helped you develop better understanding of the concept of "Convert Binary Number to Decimal and vice-versa" in C++.

Keep Learning : )

In the next Example, we will learn about C++ `Octal Number to Decimal and vice-versa`.