#include<stdio.h>
#include<string.h>
char insert(char s1[],char s2[])
{
               char s3[40]={0};
               int len1,len2, i = 0;
               len1 = strlen(s1); 
               len2 =  strlen(s2);
               for(i=0;i<len2;i++)
            {
               s3 [ i ]=s2[ i ] ;
             }
               for(i=0;i<(len1+len2);i++)
            {
               s3[i+len2]=s1;
              }
               printf("字符串2插入到字符串1后结果为：\n%s\n\n",s3);
               return s3;
}
int main()
{
              char s1[20];
              char s2[20];
              printf("请输入第一个字符串,并以回车键结束！\n");
              gets (s1);
              printf("请输入第二个字符串,并以回车键结束！\n");
              gets(s2);
              insert(s1,s2);
              return 0;
}