空白字符是指在屏幕不会显示出来的字符（如空格，制表符tab，回车换行等）。空格、制表符、换行符、回车、换页垂直制表符和换行符称为 “空白字符”，因为它们为与间距单词和行在打印的页 )的用途可以读取更加轻松。  标记分隔 (一定) 由空白字符和由其他标记，例如运算符和标点。在分析代码时， C 编译器忽略空白字符，除非使用它们作为分隔符或作为字符常数或字符串文本元素。使用空白字符使程序更易于阅读。请注意编译器还将注释作为空白。

下面贴一段c#处理空白字符的代码：

public static class TypeExtensions
    {
        // The Trim method only trims 0x0009, 0x000a, 0x000b, 0x000c, 0x000d, 0x0085, 0x2028, and 0x2029.
        // This array adds in control characters.
        public static readonly char[] WhiteSpaceChars = new char[] { (char)0x00, (char)0x01, (char)0x02, (char)0x03, (char)0x04, (char)0x05, 
            (char)0x06, (char)0x07, (char)0x08, (char)0x09, (char)0x0a, (char)0x0b, (char)0x0c, (char)0x0d, (char)0x0e, (char)0x0f, 
            (char)0x10, (char)0x11, (char)0x12, (char)0x13, (char)0x14, (char)0x15, (char)0x16, (char)0x17, (char)0x18, (char)0x19, (char)0x20,
            (char)0x1a, (char)0x1b, (char)0x1c, (char)0x1d, (char)0x1e, (char)0x1f, (char)0x7f, (char)0x85, (char)0x2028, (char)0x2029 };

        /// <summary> 
        /// Gets a value that indicates whether or not the collection is empty. 
        /// </summary> 
        public static bool IsNullOrBlank(this string s)    
        {
            if (s == null || s.Trim(WhiteSpaceChars).Length == 0)
            {
                return true;
            }

            return false;
        }

        public static bool NotNullOrBlank(this string s)
        {
            if (s == null || s.Trim(WhiteSpaceChars).Length == 0)
            {
                return false;
            }

            return true;
        }
}