"C #" integer type of judgment!

I am in the application of C # to do project when I think, textbox text box in the value of the type of judgment is not convenient, in the C#bbs to find whether there is such a class or function, but I am disappointed! So with a dull head wrote a test situation is also very satisfied, take let netizen pointing twos, if there is better, look at lease teach! Shixiang9076@sina.com.

Using System;
Using System.Drawing;
Using System.Collections;
Using System.ComponentModel;
Using System.Windows.Forms;
Using System.Data;

Namespace Winmarket
{
<summary>
Summary description of the Classfun.
</summary>
public class Classfun
{
private bool Isbool;

Public Classfun ()
{
//
TODO: Add constructor logic here
//
}
----------judge whether it is an integer-----------------
public bool Isint (string tbstr)
{
String sign= "+-";
String intstr= "1234567890";
String intsign;
int intstrsub,intindex;
int intbool=0;
Tbstr=tbstr.trim ();
if (tbstr.length==1)
{
Intstrsub=intstr.indexof (TBSTR);
if (intstrsub!=-1)
{
intbool=0;
}
Else
{
intbool=1;
}
}
else if (tbstr.length>1)
{Intindex=tbstr.indexof (".");
if (intindex==-1)
{
for (int i=0;i<=tbstr.length-1;i++)
{
intsign= tbstr.substring (i,1). ToString ();
Intstrsub=intstr.indexof (intsign);
if (i==0)
{
if (intstrsub!=-1)
{
if (intstrsub!=9)
{
intbool=0;
}
Else
{
intbool=i+1;
Break
}
}
Else
{
if (intsign== "-" | | intsign== "+")
{
intbool=0;

}
Else
{
intbool=i+1;
Break
}
}

}
Else
{
if (intstrsub!=-1)
{
intbool=0;
}
Else
{
intbool=i+1;
}

}
}


}

Else
{
intbool=1;
}
}

if (intbool==0)
{
Isbool=true;
}
Else
{
Isbool=false;
}
return isbool;

}



}
}