#include<stdio.h>
#include<string.h>
int main()
{void copystr(char *,char *,int);
int m;
char str1[20],str2[20];
printf("input string:");
gets(str1);
printf("which character that bgegin to copy?");
scanf("%d",&m);

if(strlen(str1)<m)

printf("input error!");

else {copystr(str1,str2,m);
printf("result:%s\n",str2);
}
return 0;
}


void copystr(char *p1,char *p2,int m)
{
    int n;n=0;
    while(n<m-1)
    {
        n++;
        p1++;
    }
    while(*p1!='\0')
    {
        *p2=*p1;
        p1++;
        p2++;
    }
//    *p2='\0';//如果去掉这句话，就会出现下面这种情况
}



如果不注销这句话，就不会出现这种情况！看官，请看下图