c++ - 如何在 C++ 中编写一个获取行，从文本文档中获取一行并将其添加到声明的变量中

Question

这是下面的代码 我很难在学校完成作业 我目前在获取行上遇到困难 我需要程序从文本文档中获取 0-20 中的随机行，但我似乎收到此错误，因为我无法弄清楚如何正确编写 getline

hangman2.cpp:32: 错误:没有匹配函数来调用 `getline(std::fstream&, int&)'

            #include <iostream>
            #include <fstream>
            #include <cmath>
            #include <string>

            using namespace std;

            int main() 
                {
                    string hangmantxt;
                    int randNum;
                    string word;
                    string str;     
                    randNum = rand() % 20;

                    fstream infile;

                    cout<<"enter the filename";
                    cin>>hangmantxt;
                //Ask the user for the input filename

                //Open the file (if it exists)
                    infile.open(hangmantxt.c_str());

                if(!infile)
                    {
                    cout<<"file does not exist"<<endl;
                    }



                    while(getline(infile,randNum))
                        {

                        //Pick a random number between 1 and 20 = randNum;



                        //Pick the word at located at line number = randNum in the file;
                        }       

                    /*
                    char c1, c2, c3, c4, c5, c6, c7;
                    bool a1, a2, a3, a4, a5, a6, a7;

            Assign the 7 characters in the word to each of the 7 character variables;
            Set all the Boolean variables to false;
            while ((number of missed chances < 5)||(all boolean variables are true) )
            {
            if( any of the 7 characters are vowels)
                {
                set the corresponding Boolean variable to true;
                }
            if( any of the 7 boolean variables are true)
                display the corresponding character;
            else
            display ‘_’;
            Ask the user for a single character input
            if(any of the characters match the user’s input)
            {
            set the corresponding Boolean variable to true;
            }
            if( the character did not match any of the 7 characters)
            {
            increment the number_of_chances_missed;
            }
            }
            if(number_of_chances missed >= 5)
            display “You lost!”;
            else
            display “You won!”;
            display the word;
            //These next 2 lines of code are required to set the read position of the
            input file back to the beginning of the file
            //Assuming your ifstream object is called infile
            infile.clear();
            infile.seekg(0, ios::beg);
            Ask the user if he/she wants to play again;
            }while ( the user wants to keep playing);
            */
            infile.close();
            return 0;
            }

Answer 1

有几种方法可以解决这个问题。您可以阅读该文件，直到到达您需要的行:

for (int i = 0; i < randNum; i++)
    getline(infile, str);

// now str is the randNum line from the file

您也可以读取整个文件，然后只使用 randNum 作为索引:

std::vector<std::string> lines;
while(getline(infile, str))
    lines.push_back(str);

// now lines[randNum - 1] is the randNum line of the file

如果您要在重新播放类型的情况下继续循环文件，我会使用第二种方法，除非文件很大。