爲什麼變量不變？

Question

我剛學完如何使用隨機功能，所以我決定做一個小型的賭場遊戲。但是，我的代碼不會更新double Money;變量。那就是我無法設置，添加或減去這個變量的值。我無法確定發生這種情況的原因。

這裏是我的代碼：

int main() 
{ 
    double Money;//Variable Money; 

    srand (time(0)); 
    int randomNumber; 
    randomNumber = (1+(rand() % 10)); 
    cout << "\nEnter your Starting Money: "; 
    int Guess; 
    cin >> Money; 
    cout << "Your Starting money is: " << Money; 
    cout << "\nGuess the number between 1 and 10: "; 
    start: 
    cin >> Guess; 
    if(Guess == randomNumber) 
    { 
    Money + 10; 
    cout << "You were correct! The number was " << randomNumber << "!"; 
    } 
    else 
    { 
    Money - 10;//Nothing Happens 
    cout << "You were wrong! Your money is now: " << Money << "\nRetry Please: "; 
    goto start; 
    } 
    char f; 
    cin >> f; 
    return 0; 
} 

Answer 1

Money + 10; 

是沒有副作用的聲明。你想

Money += 10; 

這相當於

Money = Money + 10; 

想想看，如果你寫

4 + 5; 

，你會想到4成爲9？ ...

Answer 2

money - 10;是一個有效的C和C++表達式，它在概念上計算該值，然後丟棄結果，與42;大致相同。代替使用money = money - 10;或money -= 10;。同樣也可以添加。

Answer 3

你需要新的谷分配給Money

Money = Money + 10或者，如前所述，Money += 10

Answer 4

金錢+ 10犯規，如果你想改變的價值用金錢改變值=金錢+ 10 你也可以使用Money + = 10 ，並用btw代替char f; cin >> f; .. cout < < endl;系統（ 「暫停」）;看起來更好