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如果我将代码分成两个单独的程序，它会像我想要的那样工作（在我创建文件的地方分隔 3 部分 #1，在我尝试以用户身份访问文件的部分 #2 中）；但是一旦我将代码放入单个程序中（见下文），我就无法使用 getline() 方法从标准输入中收集输入；该程序只是在源代码中 getline 方法所在的点处不停地收集用户输入，直到结束。

我阅读了一堆已回答的问题，并尝试以下方法无济于事：

  1. 打字#include <string>
  2. 打字outFile.clear();
  3. 打字inFile.clear();
  4. 我在过去 3 小时内尝试了其他方法，例如注释掉部分代码以查看是否可以查明问题。

该程序的目的是创建一个文本文件，然后从“老师”那里获得 2 个成绩并将它们放入文本文件中。第二部分要求用户输入文件的路径；然后代码提供文件中的平均成绩。问题是下面的代码永远不会停止允许用户输入文件的路径。

#include <iostream>
#include <fstream> //file steam for access to objects that work with files
#include <cstdlib>

//using namespace std;

int main()
{
//****************PART #1 - CREATE A FILE & ADD DATA *************************************************
std::cout << "Part #1 - create file & put data into it.\n" << std::endl;
//create an object called "outFile" of type ofstream (output file stream)
// arg #1 - path and file name
// arg #2 - constant that represents how we want to work with file (output stream in this case)
std::ofstream outFile("/home/creator/Desktop/creation.txt", std::ios::out);

//get user to enter 5 numbers:
int userGrade;
for(int i = 0; i < 2; i++)
{
    std::cout << "Enter grade number " << (i+1) << ": ";
    std::cin >> userGrade; //collect a grade from the user
    outFile << userGrade << std::endl; //write data to file (each number on it's own line)
}

outFile.close();//close the stream
std::cout << "All is well and good - file is created and data is populated" << std::endl;

//****************PART #2 - READ & MUNIPILATE DATA FROM FILE*****************************************
std::cout << "\nNext, lets read the data from the file we created." << std::endl;
std::cout << "please enter the path to the file: (ex: /home/creator/Desktop/creation.txt)" << std::endl;
std::string fileName; //the path to the file we want to read.
std::getline(std::cin, fileName);//<<< THIS IS MY QUESTION/PROBLEM
std::ifstream inFile(fileName.c_str(), std::ios::in);

if(!inFile)
{
    std::cout << "File not found!" << std::endl;
    exit(1);
}

double grade = 0;//this holds the data we retrieve from file
double total = 0; //get the sum of all the grades as a total
double average = 0; //get the average of all the grades
int numberOfGrades = 0; //number of grade values in file

//retreive and munipilate the data from the file.
while(!inFile.eof())
{
    inFile >> grade;
    total = total + grade;
    numberOfGrades++;
    std::cout << grade << std::endl;
}

average = total / numberOfGrades;
std::cout << "The average of the grades in the file is: " << average << std::endl;
inFile.close();

return 0;
}

作为代码的输出图像刚刚穿过：

在此处输入图像描述

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1 回答 1

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问题是前一个输入循环将最后一个换行符留在输入缓冲区中，下一次调用std::getline读取为空行。

这很容易通过在阅读成绩后忽略该行的其余部分来解决。

从链接参考中的示例：

std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');

在不相关的说明中，不要使用while (!inFile.eof()) { ... }，它不会像您期望的那样工作。相反，在您的情况下，您应该这样做while (inFile >> grade) { ... }。

于 2015-11-27T13:34:20.893 回答