Hex to IEEE 754

[qgeorge]

Hello,

I am trying to convert a hex value "4B3C614E" to a IEEE 754 floating point value. The correct answer to 0x4B3C614E is 12345678.00. However in C#,
I keep getting the value 1262248270. I do not have any idea how to get the
12345678.00 like is should be per the site: http://babbage.cs.qc.edu/IEEE-754/Decimal.html . My code is below:

int myHex = 0x4b3c614e;
float myFloat = System.Convert.ToSingle(myHex);

-qgeorge

[Banfa]

This C code seems to work for me

#include <stdio.h>
 
int main()
{
    float f = 12345678.0F;
    unsigned long l = *((unsigned long *)&f);
    float r = *((float *)&l);
 
    printf("%08lx <-> %.1f\n", l, r );
 
    return 0;
}
 

Note, this is completely non-portable because C does not even guarantee that a float * has the same number of bits as a unsigned long * and if they do it doesn't guarantee that they use the same bit representation.

[qgeorge]

Thanks, But I do not have a problem getting the correct answer in C. I have a poblem getting the correct answer in C#.

[Banfa]

And here is a mildly interesting C# attempt

using System;
using System.Collections.Generic;
using System.Text;
 
namespace ConsoleApplication1
{
    class Program
    {
        unsafe static void Main(string[] args)
        {
            float f = 12345678.0F;
            long l = *((long *)&f);
            float r = *((float *)&l);
 
            Console.WriteLine("{0:F1} <-> {1:X} <-> {1:F1} <-> {2:F1}", f, l, r);
        }
    }
}
 

Output

12345680.0 <-> 4B3C614E <-> 1262248270.0 <-> 12345680.0

So itr sort of gets it right except when I tell it to treat a long variable as though it were a float.

[qgeorge]

Thanks!!!!!!

[arj3090]

If using c#, why not use the BitConverter class.

In VB, it would look like this:

Dim bytes() As Byte = {&H4E, &H61, &H3C, &H4B}

Dim result As Single = BitConverter.ToSingle(bytes, 0)



more can be found at:

http://msdn2.microsoft.com/en-us/library/system.bitconverter.aspx