integer validation

Function to Test for Integers both Positive & Negative
public bool IsInteger(String strNumber)
{
Regex objNotIntPattern = new Regex("[^0-9-]");
Regex objIntPattern = new Regex("^-[0-9]+$^[0-9]+$");
return !objNotIntPattern.IsMatch(strNumber) && objIntPattern.IsMatch(strNumber);
);