> #include <iostream>
> 
> #define MAXLENGTH 100
> using namespace std;
> 
> struct BACK
> {
>     char URL[MAXLENGTH][75];
>     int top;
> };
> 
> struct FORWARD
> {
>     char URL[MAXLENGTH][75];
>     int top;
> };
> int main()
> {
>     struct BACK back;
>     struct FORWARD forward;
>     back.top = MAXLENGTH;
>     forward.top = MAXLENGTH;
>     if (back.top != 0)
>     {
>         back.top = back.top - 1;
>         strcpy(back.URL[back.top] , "http://www.acm.org/");
>     }
>     //push("http://www.acm.org/",back);
>     char command[10];
>     cin>>command;
>     while (strcmp(command , "QIUT") != 0)
>     {
>         if (strcmp(command , "VISIT") == 0)
>         {
>             char U[75];
>             cin>>U;
>             back.top = back.top - 1;
>             strcpy(back.URL[back.top] , U);
>             //push(U,back);
>             cout<<back.URL[back.top]<<endl;
>         }
>         else if (strcmp(command , "BACK") == 0)
>         {
>             if ((back.top + 1) <= (MAXLENGTH - 1))
>             {
>                 forward.top = forward.top - 1;
>                 strcpy(forward.URL[forward.top] , back.URL[back.top]);
>                 //push(back.URL[back.top],forward);
> 
>                 cout<<back.URL[back.top + 1]<<endl;
> 
>                 back.top = back.top + 1;
>                 //pop(back);
>             }
>             else
>             {
>                 cout<<"Ignored"<<endl;
>             }
>         }
>         else if (strcmp(command , "FORWARD") == 0)
>         {
>             if (forward.top <= MAXLENGTH - 1)
>             {
>                 back.top = back.top - 1;
>                 strcpy(back.URL[back.top] , forward.URL[forward.top]);
>                 //push(forward.URL[forward.top],back);
> 
>                 cout<<forward.URL[forward.top]<<endl;
> 
>                 forward.top = forward.top + 1;
>                 //pop(forward);
>             }
>             else
>             {
>                 cout<<"Ignored"<<endl;
>             }
>         }
> 
>         cin>>command;
>     }
>     return 0;
> }
栈操作应该对字符串指针进行，你对整个字符串操作，肯效率会很低！