int to hex string

Question

Use ToString("X4").

The 4 means that the string will be 4 digits long.

Reference: The Hexadecimal ("X") Format Specifier on MSDN.

Try the following:

ToString("X4")

See The X format specifier on MSDN.

Try C# string interpolation introduced in C# 6:

var id = 100;
var hexid = $"0x{id:X}";

hexid value:

"0x64"

Previous answer is not good for negative numbers. Use a short type instead of int

        short iValue = -1400;
        string sResult = iValue.ToString("X2");
        Console.WriteLine("Value={0} Result={1}", iValue, sResult);

Now result is FA88