其他沒有以前如果錯誤在c + +

-5

有人可以請解釋我在這段代碼中的上述錯誤？我在CodeBlocks中獲得它，當我使用Visual Studio時，它表示期待一個聲明。非常感謝。其他沒有以前如果錯誤在c + +

#include <iostream> 
    using namespace std; 
    int main() 
    { 
     char fruits; 
     float sales; 

     cout << " Enter the First letter of the Fruit's name : "; 
     cin >> fruits; 

     cout << " Enter the amount of sales : "; 
     cin >> sales; 


     if (fruits == 'A' || fruits == 'a') 
      cout << " You are selling Apples "; 
      cout << " Your commission is " << sales*(4.5/100) << " rupees. "; 

     else if (fruits == 'P' || fruits == 'p') 
      cout << " You are selling Pears"; 
      cout << " Your commission is " << sales*(5/100) << " rupees. "; 

     else if (fruits == 'O' || fruits == 'o') 
      cout << " You are selling Oranges "; 
      cout << " Your commission is " << sales*(5.5/100) << " rupees. "; 

     else if (fruits == 'G' || fruits == 'g') 
      cout << " You are selling Grapes "; 
      cout << " Your commission is " << sales*(6/100) << " rupees. "; 

     else 
      cout << " Invalid Entry. Try again. "; 


     return 0; 
    }

來源

2014-03-12 Peter D

如何製作包含多個語句的塊？如果你不知道，你需要回到你的書，並從頭開始閱讀。 –

C++不是Python，你知道嗎？ – 2014-03-12 16:10:20

這就好像有人在這裏爲Apple工作，不是嗎？缺少大括號連接到水果..至少在這裏，它會導致編譯器錯誤，而不是[goto失敗]（http://nakedsecurity.sophos.com/2014/02/24/anatomy-of-a-goto-fail -apples-ssl-bug-explained-plus-an-unofficial-patch /）運行時錯誤。 – stefan

您需要在您的if語句中使用括號，這樣

if (fruits == 'A' || fruits == 'a') { 
     cout << " You are selling Apples "; 
     cout << " Your commission is " << sales*(4.5/100) << " rupees. "; 
} else if (fruits == 'P' || fruits == 'p') { 

} // and so on

因爲否則你if條款將只適用於下列下一行，這將使你的邏輯看起來是這樣的：

if() 
    cout << " I am only getting executed if the above 'if' statement is true "; 
cout << " I will always be executed, no matter what ";

而且，通過這樣做，你的else聲明將在你的代碼的中間鬆，導致在你正在編譯的錯誤

if() 
    cout << " I am only getting executed if the above 'if' statement is true "; 
cout << " I will always be executed, no matter what "; 
else // but, else what? There is no 'if' behind me

來源

2014-03-12 16:09:30 streppel

謝謝，它修復了錯誤:)） –

這是因爲你有一個多行塊沒有封閉花括號。 C++將此解釋

if (fruits == 'A' || fruits == 'a') 
    cout << " You are selling Apples "; 
    cout << " Your commission is " << sales*(4.5/100) << " rupees. ";

這樣的：

if (fruits == 'A' || fruits == 'a') 
    cout << " You are selling Apples "; // Protected by `if` 
// Not protected by `if` !!! 
cout << " Your commission is " << sales*(4.5/100) << " rupees. ";

C++編譯器將忽略縮進;這就是爲什麼當您在第二個cout之後放置else時，它會被視爲else而沒有前面的if。

要解決此問題，請將所有受if s保護的塊括在花括號中。即使在不需要大括號的情況下，養成養成習慣也是一個好主意，因爲if可以保護單個陳述。

來源

2014-03-12 16:10:12 dasblinkenlight

謝謝你，它的固定:)） –

在C++中，代碼

if (fruits == 'A' || fruits == 'a') 
    cout << " You are selling Apples "; 
    cout << " Your commission is " << sales*(4.5/100) << " rupees. ";

被解釋爲

if (fruits == 'A' || fruits == 'a') cout << " You are selling Apples "; 
cout << " Your commission is " << sales*(4.5/100) << " rupees. ";

換句話說，只有第一個語句由if聲明保護。第二條聲明無條件執行。這解釋了您收到的錯誤 - else if與之前的if聲明不匹配。

爲了解決這個問題，加括號周圍的if報表的機構：

if (fruits == 'A' || fruits == 'a') { 
    cout << " You are selling Apples "; 
    cout << " Your commission is " << sales*(4.5/100) << " rupees. "; 
}

更一般地，縮進在C++無關的，所以一定要小心，以確保您的縮進你預期的意圖相符。

希望這會有所幫助！

來源

2014-03-12 16:10:24 templatetypedef

謝謝你詳細的答案。它修復了錯誤。謝謝：）） –

其他沒有以前如果錯誤在c + +

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