Check if string is empty or all spaces in C#

Question

How to easily check if a string is blank or full of an undetermined amount of spaces, or not?

Answer 1

private bool IsNullOrEmptyOrAllSpaces(string str)
{
    if(str == null || str.Length == 0)
    {
        return true;
    }

    for (int i = 0; i < str.Length; i++)
    {
        if (!Char.IsWhiteSpace(str[i])) return false;
    }

    return true;
}