C++ getchar 不能正常工作

Question

我有这段代码，它会建议用户在我的菜单中选择一个选项:

char c;
    do {
        switch(c=getchar()){
                 case '1':
                      cout << "Print" << endl;
                      break;
                 case '2':
                      cout << "Search" << endl;
                      break;
                 case '3':
                      cout << "Goodbye!" << endl;
                      break;
                 default:
                     cout << "I have this symbol now: " << c << endl;
                      break;
                }
      } while (c != '3');

因此，它假设要读取字符并将我们置于三个选项之一。确实如此。但只有在我按下 Enter 之后，好吧，我可以接受它，但它也接受这些字符串作为有效选项:

• dfds2kflds, fdsf3, fds1lkfd

什么鬼？我希望它只接受这样的字符:

• 1, 2, 3我该如何解决？我是 C++ 的菜鸟。

Answer 1

使用 getche() 或 getch()。如果你做这样的事情

c=getch();
switch(c=getch()){
             case '1':
                  cout<<c;
                  cout << "Print" << endl;
                  break;
             case '2':
                  cout<<c;
                  cout << "Search" << endl;
                  break;
             case '3':
                  cout<<c;
                  cout << "Goodbye!" << endl;
                  break;
             default:
                  break;
            }  

除了 1,2 和 3 之外，您不会在屏幕上看到任何其他字符

** 编辑 **
如果 conio.h 不可用，你可以试试这个:(丢弃行中的其余字符)

char c;
do {
    switch(c=getchar()){
             case '1':
                  cout << "Print" << endl;
                  break;
             case '2':
                  cout << "Search" << endl;
                  break;
             case '3':
                  cout << "Goodbye!" << endl;
                  break;
             default:
                 cout << "I have this symbol now: " << c << endl;
                  break;
            }
            while((c=getchar())!='\n'); //ignore rest of the line
  } while (c != '3');

或丢弃超过 1 个字符的输入

char c;
do {
    c=getchar();
    if(getchar()!='\n'){ //check if next character is newline
        while(getchar()!='\n'); //if not discard rest of the line
        cout<<"error"<<endl;
        c=0; // for case in which the first character in input is 3 like 3dfdf the loop will end unless you change c to something else like 0
        continue;
    }
        switch(c){
             case '1':
                  cout << "Print" << endl;
                  break;
             case '2':
                  cout << "Search" << endl;
                  break;
             case '3':
                  cout << "Goodbye!" << endl;
                  break;
             default:
                 cout << "I have this symbol now: " << c << endl;
                  break;
            }
  } while (c != '3');