c# how to convert float to int

Question

I need to convert float to int (single precision, 32 bits) like:
'float: 2 (hex: 40000000) to int: 1073741824'. Any idea how to implement that?
I was looking for it in msdn help but with no result.

In effect, you want a bit-wise copy? Like C++'s reinterpret_cast? — Skizz, Aug 24 '11 at 10:09
Have a look here http://stackoverflow.com/questions/2578348/c-converting-a-float-to-an-int-and-changing-the-int-depending-on-the-remain — castleofbones, Aug 24 '11 at 10:15
@castleofbones: that link is to conversions that preserve the represented number. The OP is after a conversion that preserves the binary representation. — Paul Ruane, Aug 24 '11 at 10:51

score 10 · Answer 1 · answered Aug 24 '11 at 10:32

10

float f = ...;
int i = BitConverter.ToInt32(BitConverter.GetBytes(f), 0);

answered Aug 24 '11 at 10:32

David Heffernan

601,492
42
1,072
1,490

score 2 · Answer 2 · edited May 23 '17 at 12:17

2

BitConverter.DoubleToInt64Bits, as per the accepted answer of this question.

If the above solution is no good for you (due to it acting upon double/Double rather than float/Single) then see David Heffernan's answer.

edited May 23 '17 at 12:17

Community

1
1

answered Aug 24 '11 at 10:13

Paul Ruane

37,459
12
63
82

1

question is about 4 byte float and int – David Heffernan Aug 24 '11 at 10:34

score 1 · Answer 3 · answered Aug 06 '13 at 18:04

David THANKS, that was a short answer of my long search of analogue for Java method: Float.floatToIntBits. Here is the entire code:

static void Main()
{

    float tempVar = -27.25f;

    int intBits = BitConverter.ToInt32(BitConverter.GetBytes(tempVar), 0);
    string input = Convert.ToString(intBits, 2);
    input = input.PadLeft(32, '0');
    string sign = input.Substring(0, 1);
    string exponent = input.Substring(1, 8);
    string mantissa = input.Substring(9, 23);

    Console.WriteLine();
    Console.WriteLine("Sign = {0}", sign);
    Console.WriteLine("Exponent = {0}", exponent);
    Console.WriteLine("Mantissa = {0}", mantissa);
}

score -1 · Accepted Answer · answered Aug 24 '11 at 10:17

If your aiming for versions less than .Net 4 where BitConverter isn't available, or you want to convert floats to 32 bit ints, use a memory stream:

using System;
using System.IO;

namespace Stream
{
  class Program
  {
    static void Main (string [] args)
    {
      float
        f = 1;

      int
        i;

      MemoryStream
        s = new MemoryStream ();

      BinaryWriter
        w = new BinaryWriter (s);

      w.Write (f);

      s.Position = 0;

      BinaryReader
        r = new BinaryReader (s);

      i = r.ReadInt32 ();

      s.Close ();

      Console.WriteLine ("Float " + f + " = int " + i);
    }
  }
}

It is a bit long winded though.

c# how to convert float to int

4 Answers4

Linked