串 插入删除 C语言程序代码

#include "string.h"
#include "stdio.h"
#define N 255
typedef struct string
{
   char ch[N];
   int len;
}STRING;
int Leng(STRING s)
{
   int i=0;
   int j=0;
   while(s.ch[i]!='\0')
      {
        i++;
        j++;
      }
   return(j);
}
STRING Substring(STRING s,int n1,int n2)
   {
     STRING str;
     int i;
     for(i=0;i<=n2;i++)
   str.ch[i]=s.ch[n1+i-1];
     str.len=n2;
     str.ch[i]='\0';
     return(str);
   }