Question

给我的这项任务是从我们的教科书中复制一个Hangman游戏并将其修改为书中的具体说明。我花了很多时间试图研究这个问题，并找到一个原因，我一直得到与我相同的错误信息。我看过的每一个地方，每个尝试修改此代码的人都试图使用数组并且拥有与我相同的运气。我目前正在编写Strings中的一章，并计划完成我在String中的指令所要求的大部分语句。

我需要在此代码中修改的内容是：

跟踪用户输入的所有字母
如果用户输入已输入的字母

我遇到的主要问题是，当我编译此代码并输入我已经放入的相同字母时，它会以消息终止：

在抛出'std :: out of range'的实例后终止调用 what（）：basic_string :: substr

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

    int main()
    {

        //declare variables
        string origWord = " ";
        string letter = " ";
        char dashReplaced = 'N';
        char gameOver = 'N';
        int numIncorrect = 10;
        string displayWord = "-----";
        string usedLetter = " ";
        string letterNotGuessedYet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        int letterPlace = 0;

        //get original word
        do //begin loop
        {
            cout << "Enter a 5-letter word in uppercase: ";
            getline(cin,origWord);

        }while(origWord.length() != 5); //end do loop

        //clear the screen
        system("cls");

        //start guessing
        cout <<"Guess this word: " << displayWord << endl;

        while(gameOver =='N')
        {
            cout << "Enter an uppercase letter: ";
            cin >> letter;

            //This provides the letterPlace value with the possition of the 
            //input letter by the user within letterNotGuessedYet
            letterPlace = letterNotGuessedYet.find(letter,0);

            //This statement determines if the letter input by the user is
            //still in the letterNotGuessYet string.
            if(letterNotGuessedYet.substr(letterPlace,1)== letter)
            {
                letterNotGuessedYet.replace(letterPlace, 1, "*");
                //cout << endl << letterNotGuessedYet;           //This tests that a letter is being replaced with an * 
            }                   
            else
            {
                cout << "The letter " << letter << " has already been used. Choose another letter." << endl << endl;        
            }// end if


            //search for the letter in the original word
            for(int x = 0; x < 5; x++)
            {
                //if the current character matches
                //the letter, replace the corresponding
                //dash in the displayWOrd variable and then
                //set the dashReplaced variable to 'Y'
                if (origWord.substr(x,1) == letter)
                {
                    displayWord.replace(x, 1, letter);
                    dashReplaced = 'Y';
                }//end if
            }//end for

            //if a dash was replaced, check whether the
            //displayWord variable contains any dashes

            if (dashReplaced == 'Y')
            {
                //if the displayWord variable does not
                //contain any dashes, the game is over
                if (displayWord.find("-",0) == -1)
                {
                    gameOver = 'Y';
                    cout << endl << "Yes, the word is " << origWord << endl;
                    cout << "Great guessing!" << endl;
                }

                else //otherwise, continue guessing
                {
                    cout << endl<< "Guess this word: " << displayWord << endl;
                    dashReplaced = 'N';
                }//end if

            }
            else //processed when dashReplaced contains 'N'
            {
                //minus 1 to the number of incorrect gueses left
                numIncorrect += 1;

                //if the number of incorrect guesses is 10,
                //the game is over
                if (numIncorrect == 10)
                {
                    gameOver = 'Y';
                    cout << endl << "Sorry, the word is " << origWord << endl;

                }//end if
            }//end if
        }//end while

        //system("pause");
        return 0;
    }//end of main function

我相信我收到此错误的原因与以下代码有关：

        //This provides the letterPlace value with the possition of the 
        //input letter by the user within letterNotGuessedYet
        letterPlace = letterNotGuessedYet.find(letter,0);

        //This statement determines if the letter input by the user is
        //still in the letterNotGuessYet string.
        if(letterNotGuessedYet.substr(letterPlace,1)== letter)
        {
            letterNotGuessedYet.replace(letterPlace, 1, "*");
            //cout << endl << letterNotGuessedYet;           //This tests that a letter is being replaced with an * 
        }                   
        else
        {
            cout << "The letter " << letter << " has already been used. Choose another letter." << endl << endl;        
        }// end if

我很感激你可以带来任何帮助。

Answer 1

您收到错误的原因是因为您正在使用＆＃34; letterPlace＆＃34;测试之前的值，看它是否真的被发现。如果＆＃34; string :: find＆＃34;没有找到任何会返回值的东西＆＃34; string :: npos＆＃34;。在尝试使用它之前，您需要测试letterPlace vairable值。

letterPlace = letterNotGuessedYet.find(letter,0);

// Check to see if this letter is still in the "letterNotGuessedYet string
if(letterPlace != string::npos)
{
    // At this point the letter is in the letterNotGuessedYet string so let it go
    letterNotGuessedYet.replace(letterPlace, 1, "*");
}
else
{
    // The letter was not found which means it has already been guessed.
    // Show error to the user here
    cout << "The letter " << letter << " has already been used. Choose another letter." << endl << endl;
}

如何跟踪已经在Hangman游戏中为C ++猜到的字母？

1 个答案: