测试一个函数，其功能是搜索由函数的第一个参数指定的字符串，在其中查找由函数的第二个参数指定的字符的第一次出现的位置。如果找到，返回指向这个字符的指针：如果没有找到，返回空字符(这种方式和strchr()函数的功能一样）。-Test a function, its function is to search for the string specified by the first parameter of the function and location in which to find the first occurrence of the character specified by the second argument of the function. If found, return the pointer to point to this character: if not found, return null character (in this way and the strchr () function does the same).