在學校任務中​​遇到問題

Question

這段代碼中有一些崩潰錯誤，我應該找到，但我有問題發現它們，我花了很長時間纔看到。我相信這很容易，我失蹤了。當我運行在Visual Studio 2012的代碼中，我得到與數組下標錯誤

#include <iostream> // provides access to cin and cout 
#include <iomanip> 
#include <array> 

#include <vector> 


using namespace std; 

int main() 
{ 
    // seed random number generator 
    srand(time(NULL)); 

enum symbol 
{ 
    Lemon, Cherry, Orange, Bell, Jackpot 
}; 
// create a struct for slot machine wheel 
struct Wheel 
{ 
    array <string, 10> symbols; 
    array <symbol, 10> eSymbols; 
    int position; 
    string selected; 
}; 
//create an array of three slot machine wheels 
array <Wheel, 3> slotMachine = 
{ 
    { 
     { 
      {"Cherry", "Orange", "Lemon", "Orange", "Bell", "Orange", "Lemon", "Cherry", "Jackpot", "Bell"}, 
      {Cherry, Orange, Lemon, Orange, Bell, Orange, Lemon,Cherry, Jackpot, Bell}, 
      0,"Cherry" 
     }, 
     { 
      {"Cherry", "Bell", "Lemon", "Orange", "Bell", "Jackpot", "Lemon", "Cherry", "Jackpot", "Bell"}, 
      {Cherry, Bell, Lemon, Orange, Bell, Jackpot, Lemon, Cherry, Jackpot, Bell}, 
      1,"Bell" 
      }, 
      { 
       {"Cherry", "Orange", "Lemon", "Orange", "Lemon", "Orange", "Lemon","Cherry", "Jackpot", "Bell"}, 
       {Cherry, Orange, Lemon, Orange, Lemon, Orange, Lemon, Cherry, Jackpot, Bell}, 
       2,"Lemon" 
      } 
    } 
}; 

bool gameOn = true; 
bool winner = false; 
int thePot = 100; 
int bet = 1; 
vector <int> combo; 
while (gameOn) 
{ 
    for (int i = 1; i < 4; i++) 
    { 
     slotMachine[i].position =(slotMachine[i].position + rand()%10)%10; 
     slotMachine[i].selected = slotMachine[i].symbols[slotMachine[i].position]; 
     cout << setw(10) << left << slotMachine[i].selected.c_str() ; 
     combo.push_back(slotMachine[i].eSymbols[slotMachine[i].position]); 
    } 
    if ((combo[0] == combo[1]) && (combo[1] == combo[2])) 
    { 
     if (combo[0] == Lemon) 
     { 
      cout << "You keep your bet." << endl; 
     } 
     else if(combo[0] = Jackpot) 
     { 
      cout << "**** You hit $1000 Jackpot!!! ****" << endl; 
      thePot += 1000; 
      winner = true; 
      gameOn = false; 
     } 
     else 
     { 
      cout << "WINNER! You win $" << combo[0]*5 << endl; 
      thePot += combo[0]*5; 
     } 
    } 
    else 
    { 
     thePot -= bet; 
     if (thePot > 0) gameOn=false; 
    } 
    cout << "You now have $" << thePot << endl; 
    combo.clear(); 
    cout << endl; 
    cin.get(); 
} 
if (winner) cout << "You walk away a winner." << endl; 
else cout << "You have lost all your money." << endl; 
// Wait for user input to close program when debugging. 
cin.get(); 
return 0; 

Answer 1

你宣佈一個

array <Wheel, 3> slotMachine; 

之後，你通過這個數組反覆如下：

for (int i = 1; i < 4; i++) 
{ 
    slotMachine[i].position = 

此代碼根據循環的邏輯，將訪問slotMachine[1]到slotMachine[3]。

不幸的是，沒有slotMachine[3]，試圖訪問它會導致未定義的行爲，並可能導致崩潰。

N元素的數組或向量包含編號從0到N-1的元素。你可以用你的手指來驗證這個事實。

此數組包含slotMachine[0]到slotMachine[2]，而不是slotMachine[1]到slotMachine[3]。這就是數組和向量在C++中的工作原理。