实现顺序串各种基本算运算，建立串，输出串，输出它的长度，插入，删除，替换，提取，把两个串连接成一个串-String order to achieve a variety of basic counting operations, the establishment of string, the output string, the output of its length, insert, delete, replace, extract, the two strings into a stri

编写一个程序algo4-1.cpp，实现顺序串的各种基本运算，并在此基础上设计一个主程序完成如下功能-Write a program algo4-1.cpp, in order to achieve a variety of basic string operations, and on this basis, following the completion of the design features a main program