Building a 32-bit float out of its 4 composite bytes

Question

I\'m trying to build a 32-bit float out of its 4 composite bytes. Is there a better (or more portable) way to do this than with the following method?

#includ         


        

Answer 1

If you want a portable way to do this, you'll have to write a bit of code to detect the endianess of the system.

float bytesToFloatA(uchar b0, uchar b1, uchar b2, uchar b3)
{
    float output;

    *((uchar*)(&output) + 3) = b0;
    *((uchar*)(&output) + 2) = b1;
    *((uchar*)(&output) + 1) = b2;
    *((uchar*)(&output) + 0) = b3;

    return output;
}


float bytesToFloatB(uchar b0, uchar b1, uchar b2, uchar b3)
{
    float output;

    *((uchar*)(&output) + 3) = b3;
    *((uchar*)(&output) + 2) = b2;
    *((uchar*)(&output) + 1) = b1;
    *((uchar*)(&output) + 0) = b0;

    return output;
}

float (*correctFunction)(uchar b0, uchar b1, uchar b2, uchar b3) = bytesToFloatA;

if ((*correctFunction)(0x3e, 0xaa, 0xaa, 0xab) != 1.f/3.f) // horrifying, I know
{
  correctFunction = bytesToFloatB;
}