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Infinite loop with cin when typing string while a number is expected（4个答案）
2天前关闭。
试图创建一个菜单，但使其只接受整数来选择选项，并在用户输入字母时返回。
AppUI.cpp

#include <iostream>
#include <windows.h>
#include <iomanip>
#include <string>
#include <cstring>
#include <algorithm>
#include <unistd.h>
#include <stdio.h>

using namespace std;

void AppUI::SearchBook()
{
    system("CLS");
    TitleHeader();
    setTxtColor(10);
    PageTitle("Search Book");

    cout << "Search books by:" << endl;
    cout << "1. Title" << endl;
    cout << "2. Author" << endl;
    cout << "3. Publication Date" << endl;
    cout << "4. Publisher" << endl;
    cout << "\n0. Go back to main menu" << endl;
}

EditBook.cpp

#include <iostream>
#include <windows.h>
#include <iomanip>
#include <string>
#include <cstring>
#include <algorithm>
#include <unistd.h>
#include <stdio.h>

using namespace std;

void EditBook::SearchBook()
{
    //variable declarations
    int Opt;
    char searchTxt[255];

    SearchStart:
    UI.SearchBook();
    cout << "\nOption: ";
    cin >> Opt;

    switch(Opt)
    {
        case 0:
            UI.MainMenu();
            break;

        case 1:
            system("CLS");
            cout << "Enter title: ";
            cin.getline(searchTxt,sizeof(searchTxt));
            SearchByTitle(searchTxt);
            break;

        case 2:
            system("CLS");
            cout << "Enter author name: ";
            cin.getline(searchTxt,sizeof(searchTxt));
            SearchByAuthor(searchTxt);
            break;

        case 3:
            system("CLS");
            cout << "Enter publication date: ";
            cin.getline(searchTxt,sizeof(searchTxt));
            SearchByPubDate(searchTxt);
            break;

        case 4:
            system("CLS");
            cout << "Enter publisher: ";
            cin.getline(searchTxt,sizeof(searchTxt));
            SearchByPublisher(searchTxt);
            break;

        default:
            cout << "Invalid option!";
            sleep(1);
            goto SearchStart;
            break;
    }
}

在搜索书中，当我输入一个选项中没有的数字，比如“5”，它会循环回来，让我输入正确的选项。但是当我输入一个字母，比如“a”，它会循环回来，让它一遍又一遍地显示“无效选项”，不让我输入新的选项。我希望当我输入一个字母，这是一个无效选项，它仍然会返回并让我输入正确的一个，这是一个数字/整数。