程序代码：

#include<stdio.h> 
void main()
{  
    int n1,n2,i;
    char string1[40],*pstr,string2[40];
    fputs("please input a string.\n",stdout);
    gets(string1);
    fputs("please type the number you want to use.\n",stdout);
    scanf("%d,%d",&n1,&n2);
    pstr=string1;
    for( i=0;i<n1;i++ )
        pstr++;
    for( i=0;i<(n2-n1);i++ )
        *(string2+i)=*(pstr+i);
    *(string2+i)='\0';
    puts(string2);
}