C ++：是否無法根據條件結束循環？

Question

該代碼用於運行三次循環，該循環將收集的卵數取走並輸出數十個或更多的卵，直到用戶輸入負數為止。 然后，它打印出收集（輸入）的雞蛋的平均數量，並輸出幾十個及更多的雞蛋總數。

我們分配給使用的輸入是：43、31，-1、24、8、14，-999，-5。

一切正常，直到我們輸入-5。 我們的老師不希望打印幾十個附加項目的平均值或總數（您會在輸出中看到我的意思）。

源代碼如下：

#include <iostream>
#include <iomanip>
using namespace std;

int main ()
{
    int   eggNum;
    int   eggDozens;
    int   eggExtra;
    int   eggTotal;
    int   loopCount;
    int   forCount;
    float eggAvg;
    int   totalDozens;
    int   totalExtra;

    for(forCount = 1; forCount <= 3; forCount=forCount + 1)
    {
        cout << left << "TEST #" << forCount << ":" << endl;
        cout << "Welcome to Aunt Ellen\'s eggs to dozens converter!";
        cout << endl << endl;
        cout << "\tEnter the number of eggs gathered: ";
        cin  >> eggNum;

        eggTotal  = 0;
        loopCount = 0;

        while(eggNum >= 0)
        {
            eggDozens = eggNum / 12;
            eggExtra  = eggNum % 12;

            if(eggDozens != 0)
            {
                if(eggExtra != 0)
                {
                    cout << "\tYou have " << eggDozens << " dozen ";
                    cout << eggExtra << " eggs.";
                    cout << endl << endl;
                }
                else
                {
                    cout << "\tYou have " << eggDozens << " dozen eggs.";
                    cout << endl << endl;
                }
            }
            else
            {
                cout << "\tYou have " << eggExtra << " eggs.";
                cout << endl << endl;
            }

            loopCount = loopCount + 1;
            eggTotal  = eggTotal + eggNum;

            cout << "\tEnter the number of eggs gathered: ";
            cin  >> eggNum;
        }
        cout << endl << "TOTALS:" << endl;
        eggAvg = eggTotal / float(loopCount);
        cout << "\tOn average " << eggAvg << " eggs have been";
        cout << " gathered.";

        totalDozens = eggTotal / 12;
        totalExtra  = eggTotal % 12;

        cout << endl << "\tA total of " << totalDozens << " dozen ";
        cout << totalExtra << " and eggs have been gathered!" << endl;
        cout << endl << endl;
    }

    return 0;
}

並輸出：

TEST #1:
Welcome to Aunt Ellen's eggs to dozens converter!

    Enter the number of eggs gathered: 43
    You have 3 dozen 7 eggs.

    Enter the number of eggs gathered: 31
    You have 2 dozen 7 eggs.

    Enter the number of eggs gathered: -1

TOTALS:
    On average 37 eggs have been gathered.
    A total of 6 dozen 2 and eggs have been gathered!


TEST #2:
Welcome to Aunt Ellen's eggs to dozens converter!

    Enter the number of eggs gathered: 24
    You have 2 dozen eggs.

    Enter the number of eggs gathered: 8
    You have 8 eggs.

    Enter the number of eggs gathered: 14
    You have 1 dozen 2 eggs.

    Enter the number of eggs gathered: -999

TOTALS:
    On average 15.3333 eggs have been gathered.
    A total of 3 dozen 10 and eggs have been gathered!


TEST #3:
Welcome to Aunt Ellen's eggs to dozens converter!

    Enter the number of eggs gathered: -5

TOTALS:
    On average -1.#IND eggs have been gathered.
    A total of 0 dozen 0 and eggs have been gathered!

我不想要最后一個“ TOTALS”和以下各行。 我希望程序在輸入-5后終止。

Answer 1

最簡單的事情是在進入while循環之前執行此操作：

cin  >> eggNum;

if (eggNum < 0)
    break ;

那將退出for循環，並return 0;

如果需要，可以在調用break之前向調用者添加一些有關輸入負數的注釋。

Answer 2

您提到您只想省略TOTALS的最后一塊。

您可以簡單地添加一個特殊情況以在這種情況下盡早離開外循環。

就在此塊之前，但在 while循環的右括號之后 。

cout << endl << "TOTALS:" << endl;
        eggAvg = eggTotal / float(loopCount);

插入此：

if (forCount == 3) break;

如果您只想避免在平均值小於0打印，則應在同一位置插入。

if (eggAvg < 0) continue;

這將跳過for循環的其余迭代。

Answer 3

我認為對您的問題的一個簡單答案是僅在打印總代碼周圍放置一個if語句。 像這樣：

   if(eggNum > -5){ //won't print for negative 5

    cout << endl << "TOTALS:" << endl;
    eggAvg = eggTotal / float(loopCount);
    cout << "\tOn average " << eggAvg << " eggs have been";
    cout << " gathered.";

    totalDozens = eggTotal / 12;
    totalExtra  = eggTotal % 12;

    cout << endl << "\tA total of " << totalDozens << " dozen ";
    cout << totalExtra << " and eggs have been gathered!" << endl;
    cout << endl << endl;
    } 

我希望這有幫助！