char a[]="hallo"; string b="hello"; cout<<strcmp(a,b);
int strcmp(const char*, const char*)’的实参‘2’从‘std::string* {aka std::basic_string<char>*}’转换到‘const char*’
strcmp是针对char字符串的操作，不适用于string串
char a[]="222hello"; char b[]="222hallo"; cout<<strcmp(a,b);
输出4