Convert decimal fraction to binary number - GeeksforGeeks

Convert decimal fraction to binary number - GeeksforGeeks
Given an fraction decimal number n and integer k, convert decimal number n into equivalent binary number up-to k precision after decimal point.

Input: n = 2.47, k = 5
Output: 10.01111

Time complexity: O(len(n))
Auxiliary space: O(len(n))

string decimalToBinary(double num, int k_prec)

{

    string binary = "";

 

    // Fetch the integral part of decimal number

    int Integral = num;

 

    // Fetch the fractional part decimal number

    double fractional = num - Integral;

 

    // Conversion of integral part to

    // binary equivalent

    while (Integral)

    {

        int rem = Integral % 2;

 

        // Append 0 in binary

        binary.push_back(rem +'0');

 

        Integral /= 2;

    }

 

    // Reverse string to get original binary

    // equivalent

    reverse(binary.begin(),binary.end());

 

    // Append point before conversion of

    // fractional part

    binary.push_back('.');

 

    // Conversion of fractional part to

    // binary equivalent

    while (k_prec--)

    {

        // Find next bit in fraction

        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;

}

http://www.geeksforgeeks.org/convert-binary-fraction-decimal/

Given an string of binary number n. Convert binary fractional n into it’s decimal equivalent.

Input: n = 110.101
Output: 6.625

double binaryToDecimal(string binary, int len)

{

    // Fetch the radix point

    size_t point = binary.find('.');

 

    // Update point if not found

    if (point == string::npos)

        point = len;

 

    double intDecimal = 0, fracDecimal = 0, twos = 1;

 

    // Convert integral part of binary to decimal

    // equivalent

    for (int i = point-1; i>=0; --i)

    {

        // Subtract '0' to convert character

        // into integer

        intDecimal += (binary[i] - '0') * twos;

        twos *= 2;

    }

 

    // Convert fractional part of binary to

    // decimal equivalent

    twos = 2;

    for (int i = point+1; i < len; ++i)

    {

        fracDecimal += (binary[i] - '0') / twos;

        twos *= 2.0;

    }

 

    // Add both integral and fractional part

    return intDecimal + fracDecimal;

}

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