Textbox only allow ints, but also negative ints as well as positive

How would one do this easily?

I figured positive only can be done by

Code (csharp):

1.  
2. tempText = GUI.TextField(Rect(0,0,100,100), amt.ToString());
3.     temp = 0;
4.     if (int.TryParse(tempText,temp))
5.     {
6.         amt = Mathf.Clamp(temp, -90, 90);
7.         Debug.Log("Vaild");
8.     }
9.  

but it doesn't allow for negative numbers to be entered

 

Well actually this works but if the number if negative but not if you start by typing -

 

Why not just use a slider and typecast to int?
http://docs.unity3d.com/Documentation/ScriptReference/GUILayout.HorizontalSlider.html

 

Because someone designed interface and I am just implementing it

I figured how to but my code isn't very elegant.

 

Love this kind of challenge;

Code (csharp):

1.  
2. public class NumberTextField
3. {
4.     private string temp = "";
5.     private float value = 0;
6.     private string format = "";
7.  
8.     public NumberTextField() { }
9.  
10.     public NumberTextField(string format)
11.     {
12.         this.format = format;
13.     }
14.  
15.     public float Draw(string label, float value)
16.     {
17.         if (this.value != value)
18.         {
19.             this.value = value;
20.             temp = value.ToString();
21.         }
22.  
23.         GUILayout.Label(label);
24.         string input = GUILayout.TextField(temp);
25.  
26.         float result;
27.         if (float.TryParse(input, out result)  !float.IsInfinity(result))
28.         {
29.             temp = result.ToString(format);
30.             return result;
31.         }
32.  
33.         if (input.Length == 0 || (input.Length == 1  input.StartsWith("-")))
34.         {
35.             temp = input;
36.             return 0;
37.         }
38.  
39.         return value;
40.     }
41. }
42.  

Right now it's in float, but should be simple enough to turn into integer.
This class is reusable wherever you want it.