问题是在switch语句中调用函数时似乎永无休止的循环（即使函数不包含循环）

Question

我正在尝试使用switch语句为类分配一个非常简单的文本菜单。问题是在调用我在switch语句的不同情况下所做的各种函数时，它们似乎永远不会结束。

考虑到同一个问题似乎在我的switch语句中的所有函数上都发生了，我认为这可能与switch语句本身有关，而不是与单个函数有关，尽管老实说我现在还不知道。

免责声明：我知道我的代码还有很多其他问题，但我只是想为简单起见选择一个大问题。我也希望在代码的其他部分提供建议。 （还没有完成，您可能会从未完成的案例中看到）

示例输出：

==================
1. Admission's Office
2. Student
3. End Program
==================
Enter your choice: 1

Enter the password: 123

******************
1. Add a new student
2. Add new students from a file
3. Drop a student
4. View one students info
5. View all students info
******************
Enter your choice: 1

Enter the first name: First Name

Enter the last name: Last Name

Enter the gender: m

Enter the first name: It should only ask me once

Enter the last name: Why is this looping?

Enter the gender: ????

Enter the first name:
Enter the last name: ???????

Enter the gender: a

Enter the first name: ^C

代码

//main.cpp
int main() {
  Student stuAr[SIZE];
  int choice, password, userInput;
  int numStu = 0;
  bool valid;

  do {
    userMenu();
    cin>>choice;
    cout<<endl;

    switch(choice){
    case 1:
      cout<<"Enter the password: ";
      cin>>password;
      cout<<endl;

      valid = checkPass(password);
      if (valid) {
        adminMenu();
        cin>>choice;
        cout<<endl;

        do {
          switch(choice) {
          case 1:
            addStu(stuAr, numStu);
            break;

          case 2:
            addStuFile(stuAr, numStu);
            break;

          case 3:
            cout<<"Enter the student ID: ";
            cin>>userInput;
            cout<<endl;
            dropStu(stuAr, numStu, userInput);
            break;

          case 4:
            cout<<"Enter the student ID: ";
            cin>>userInput;
            cout<<endl;
            viewStu(stuAr, numStu, userInput);
            break;

          case 5:
            viewAllStu(stuAr, numStu);
            break;
          }
        }while(choice != 6);
      }
      else {
        cout<<"The password is wrong."<<endl;
      }
      break;

    case 2:

      break;
    }
  }while(choice != 3);

  return 0;

//still main.cpp
//addStu function for case 1 of the nested switch statement
void addStu(Student stuAr[], int& numStu) {
  cin.ignore();
  cout<<"Enter the first name: ";
  stuAr[numStu].setFN();
  cout<<endl;

  //cin.ignore();
  cout<<"Enter the last name: ";
  stuAr[numStu].setLN();
  cout<<endl;

  cout<<"Enter the gender: ";
  stuAr[numStu].setGender();
  cout<<endl;

  numStu++;
  return;
}

Answer 1

您永远不会在内部循环中重新读取choice。

if (valid) {
adminMenu();
cin>>choice; // only done once, therefore do loop never terminates
cout<<endl;
do {
  switch(choice) {
  case 1:
    addStu(stuAr, numStu);
    break;
  // ...
  }
  // after switch-case, add:
  cin >> choice;
  cout << endl;

Answer 2

您永远不会在内部choice循环中更改do..while，因此条件choice != 6将始终为true，除非您是第一次输入。