開關語句輸出成本錯誤值

Question

當我嘗試在Microsoft Visual Studio C++上運行此代碼時;它運行但是輸出的成本值是錯誤的。這是爲什麼？我意識到我沒有包括一個默認語句，並且我聲明瞭cost兩次，這是因爲我得到的調試錯誤cost沒有聲明值，所以我假設的是switch語句沒有處理，因爲它有些如何不理解
cout << "Pizza"; 我該如何解決這個問題？

#include "stdafx.h" 
#include <iostream> 
#include <iomanip> 
#include <cmath> 
#include <cstdlib> 
#include <time.h> 
#include <Windows.h> 
#include <string> 

using namespace std; 

int main() 
{ 
    int a, b, c, d, e, f, m, p, k, User_Input, Pizza , cost; 
    a = 0; 
    b = 0; 
    c = 0; 
    d = 0; 
    e = 0; 
    f = 0; 
    k = 0; 
    cost = 0; 

    cout << "What is your favorite vegetarian food from the list below?" << endl; 
    Sleep(1500); 
    cout << "Pizza\n"; 
    Sleep(200); 
    cout << "IceCream\n"; 

    cin >> User_Input; 
    switch (User_Input) 
    { 
    case 1: 
     cout << "Pizza"; 
     cost = 5; 
     break; 
    case 2: 
     cout << "IceCream"; 
     cost = 5; 
     break; 

    } 


    Sleep(2000); 
    cout << "The total cost will be: " << cost; 
    cout << "\n\n\n\t\t\t"; 

    return 0; 


} 

Answer 1

User_Input是「int」類型，如果您嘗試通過cin讀取字符串到該變量，您將獲得意想不到的結果。你可能想要做什麼或者是：

• 讀入一個字符串，做一個字符串比較
• 讀入到一個字符串轉換爲int，並做switch語句

簡化例如：

#include <iostream> 
#include <string> 
int main() 
{ 
     std::string user_input; 
     int cost = 0; 
     std::cout << "What is your favorite vegetarian food from the list below?\nPizza\nIceCream\n"; 
     std::cin >> user_input; 
     if(user_input == "Pizza") { 
       cost = 5; 
     } else if (user_input == "IceCream") { 
       cost = 10; 
     } 
     std::cout << "The total cost will be: " << cost << std::endl; 
     return 0; 
}