如何在 C++ 中编写一条获取行，从文本文档中获取一行并将其添加到声明的变量中答案

【问题标题】：How do write a get line in c++ that grabs a line from a text document and adds it to a declared variable如何在 C++ 中编写一条获取行，从文本文档中获取一行并将其添加到声明的变量中
【发布时间】：2015-04-10 15:21:08
【问题描述】：

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在文本文档中从 0-20 中抓取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;
            }

【问题讨论】：

您将randNum 传递给getline，而不是字符串。
getline 用于字符串。
你应该将文件逐行读入一个向量，然后使用随机数索引该向量。

标签： c++

【解决方案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

如果您要在再次播放的情况下继续循环播放文件，除非文件很大，否则我会使用第二种方法。

【讨论】：