#include<stdio.h>#include<string.h>int main(){ int i=0; char g; char str1[50] = { "Welcome to GDUT," }; char str2[] = { "my friend" }; while (i <= 15)//-----------------------循环加switch语句进行各字符串函数的操作，有疑问：为什么要循环十五次才能出现6个结果？ { scanf_s("%c", &g, sizeof(g)); switch (g) { case'A':printf("%s", strcat(str1, str2));break; case'B':printf("%s", strncat(str1, str2, 2));break; case'C':printf("%s", strcpy(str1, str2));break; case'D':printf("%s", strncpy(str1, str2, 2));break; case'E':printf("str2字符串长度为%d", strlen(str2));break; case'F':printf("%d", strcmp(str1, str2));break; default:putchar('\a'); } i++; } return 0;}