To check string is palindrome or not in .NET (C#)

There's no need to compare each character of the string separately:

public static bool IsPalindrome(string str, StringComparison comparisonType)
{
    if (string.IsNullOrEmpty(str)) return false;
    string str2 = new string(str.Reverse().ToArray());
    return string.Equals(str, str2, comparisonType);
}
public static bool IsPalindrome(string str)
{
    return IsPalindrome(str, StringComparison.OrdinalIgnoreCase);
}