合并

代码说明：

  有两个磁盘文件A和B,各存放一行字母,要求把这两个文件中的信息合并(按字母顺序排列), 输出到一个新文件C中。(There are two disk files A and B, each storing a line of letters, requiring that the information in the two files be combined (in alphabetical order) and output to a new file C.)