请编写函数fun，函数的功能是：将放在字符串数组中的M各字符串（每串的长度不超过N），按顺序合并组成一个新的字符串。函数fun中给出的语句仅供参考。

例如，字符串数组中的M个字符串为

AAAA

BBBBBBB

CC

则合并后的字符串的内容应是：AAAABBBBBBBCC。

提示：strcat(a,b)的功能是将字符串b复制到字符串a的串尾上，成为一个新串。

注意：部分源程序在文件APROG1.C中。

请勿改动主函数main和其它函数中的任何内容，仅在函数fun的花括号中填入你编写的若干语句。-Please write the function fun, function is the function: string array will be placed in the M of string (the length of each string of not more than N), merged in order to form a new string. Function fun statement given for reference only. For example, the string array of M string AAAA BBBBBBB CC is the combined contents of the string should be: AAAABBBBBBBCC. Tip: strcat (a, b) function is copied into the string b string on the end of a string, a new string. Note: Some source code in the file APROG1.C. Do not change main function and other functions in any content, only the braces in the function fun fill a number of statements you write.