# Convert decimal fraction to binary number in C++

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In this tutorial, we will be discussing a program to convert decimal fraction to a binary number.

For this we will be provided with a decimal fraction and integer ‘k’. Our task is to convert the given decimal fraction into its binary equivalent upto the given ‘k’ digits of decimal precision.

## Example

Live Demo

#include<bits/stdc++.h>
using namespace std;
//converting decimal to binary number
string convert_tobinary(double num, int k_prec) {
string binary = "";
//getting the integer part
int Integral = num;
//getting the fractional part
double fractional = num - Integral;
//converting integer to binary
while (Integral) {
int rem = Integral % 2;
binary.push_back(rem +'0');
Integral /= 2;
}
//reversing the string to get the
//required binary number
reverse(binary.begin(),binary.end());
binary.push_back('.');
//converting fraction to binary
while (k_prec--) {
fractional *= 2;
int fract_bit = fractional;
if (fract_bit == 1) {
fractional -= fract_bit;
binary.push_back(1 + '0');
} else
binary.push_back(0 + '0');
}
return binary;
}
int main() {
double n = 4.47;
int k = 3;
cout << convert_tobinary(n, k) << "\n";
n = 6.986 , k = 5;
cout << convert_tobinary(n, k);
return 0;
}

## Output

100.011
110.11111