CODEWITHSUNDEEP
cbit-manipulation
user13191962
user13191962

Reputation:

Minor error with extracting the fraction part of an IEEE 754 floating format number

So I have this function where I extracted my fraction part of the given int so that I can output it in hex form.

Here is my code where result is the fraction part which I then print in hex form.

// getting fraction part
    result = 0;
    int count = 0;
    for (int which_digit = 23; which_digit >0; which_digit--) {
        shifted_value = f >> (23 - count);
        int fractionn = (shifted_value & 1) * (1 << which_digit) ;
        result += fractionn;
        count++;
    }

If I'm given the number 8, my program correctly prints the hex form of the fraction part. However given another number like -0.749000013, my program prints 0x3fbe76 instead of 0x3fbe77.

Does anyone know where I went wrong

Upvotes: 0

Views: 43

Answers (1)

interjay
interjay

Reputation: 110088

Your loop end condition is which_digit > 0, so you skip over bit #0. It should be which_digit >= 0. You should also start with bit 22, not 23.

That said, your entire loop can be replaced by the simple result = f & 0x7fffff;. There's no need to go bit by bit.

Upvotes: 1

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