#include
int main()
{
char *s1="1234567890abcdefghijklmnop";
char s2[50];
//或者 char s1[200],s2[200];下面再用gets(s1);读取s1
int i,j,m,n;
printf("input m n:");
scanf("%d%d",&m,&n);
for(j=0,i=m-1;i s2[j++]=s1[i++]; s2[j]='\0'; puts(s2); system("pause"); }