std::string并没有提供所有需要方法。所以，需要用STL提供了算法库、字符串流以及现存的std::string的方法来实现它们。

※ 将字符串转换为大写／小写

※ 去掉字符串两端的空格

※ 忽略大小写比较字符串

※ StartsWith和EndsWith

※ 从字符串解析出int和bool等类型的值

※ 将各种数值类型转换成字符串(toString)

※ 拆分字符串和Tokenizer-std:: string does not provide all the necessary means. Therefore, the need to use STL provides a library of algorithms, string streams, as well as the existing std:: string methods to achieve them.

※ convert a string to uppercase/lowercase

※ remove the spaces at both ends of the string

※ Comparison of strings ignoring case

※ StartsWith and EndsWith

※ From the string parsing out the int and bool types of values such as

※ all kinds of numeric type conversion into a string (toString)

※ split strings and Tokenizer