8.编写一个函数，实现两个字符串的比较，即自己写一个stringcmp 函数：stringcmp(s1,s2)。如果s1=s2，返回置为0；如果s1≠s2，返回它们二者第一个不同字符的ASCII码差值（如“BOY“与”BAD“第二个字母不同，”O“和”A”之差为79-65=14）；如果s1>s2，则输出正值；如s1<s2，则输出负值，在主函数中输入字符串以及输出上述结果。（要求使用指针实现）- Write a function that compares two strings to achieve, that is to write a function stringcmp: stringcmp (s1, s2). If s1 = s2, return is set to 0　if s1 ≠ s2, returning them both the first difference of different characters in ASCII (such as　BOY　and　BAD　different　the second letter,　O　and　A　the difference is 79-65 = 14)　if s1> s2, the output value　as s1 <s2, a negative value is output, the input string in the main function and outputs the result. (Requires the use of pointers)