#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int main()
{int i,n,j;
char s[20];
srand(time(NULL));
printf("产生20组字符串:\n");
for(j=0;j<20;j++){
s[0]=65+rand()%26; //以下4行确保含有大小写字母、数字和符号
s[1]=48+rand()%10;
s[2]=33+rand()%15;
s[3]=97+rand()%26;
n=rand()%9+4;
for(i=4;i<n+4;i++) //保证总长度为8~16
s[i]=33+rand()%94;
s[i]='\0';
printf("%s\n",s);
}
return 0;
}