查找文件位置

从键盘中输入str1和str2，查找str1字符串中第一个不属于str2字符串中字符的位置，并将该位置输出；再从键盘中输入str3和str4，查找在str3中是否包含str4，无论包含与否给出提示信息。

#include<stdio.h>#include<string.h>int main(){char str1[30], str2[30], str3[30], str4[40], *p;int pos;printf("Please input string1: ");gets(str1);printf("Please input string2: ");gets(str2);pos=strspn(str1,str2);printf("The position you want to find is: %d\n",pos);printf("Please input string3: ");gets(str3);printf("Please input string4: ");gets(str4);p=strstr(str3,str4);if(p){printf("str3 include str4\n");}else{printf("can not find str4 in str3!");}printf("\n");return 0;}