a simple code of allowing only one decimal in c# code example

Example: how to convert a number to 2 decimal places in c#

// just two decimal places
String.Format("{0:0.##}", 123.4567);      // "123.46"
String.Format("{0:0.##}", 123.4);         // "123.4"
String.Format("{0:0.##}", 123.0);         // "123"