C ++从txt文件中读取getline并存储到字符串数组中答案

【问题标题】：C++ Read getline from txt file and store into string arrayC ++从txt文件中读取getline并存储到字符串数组中
【发布时间】：2021-10-25 07:52:35
【问题描述】：

我正在使用 (getline(MyFile, line)) 从文本文件中读取文本文件，并希望将其存储在每个元素的字符串数组中。我的代码无法正常工作。基本上，我需要从文件中读取，将每一行保存到一个字符串数组中，然后在每个元素处遍历每个字符串。 for 循环也没有增加到 4，我不知道为什么。请帮忙。

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

int array[16], i;
fstream myFile;
string filename, line, str[256];

int main() {

    // 1. The user will enter the full name of the file
    cout << "Enter the file name to open: ";
    cin >> filename;
    getchar();  // clear the input buffer before reading the filename

    // 2. Open the file for reading (input)
    myFile.open(filename.c_str(), fstream::in);

    // only continue if the file has opened successfully
    if (myFile.is_open() == false) {
        cout << "ERROR: not able to open " << filename << endl;
    }
    else {
        // 3. Access the file - read all the lines from the file
        for (i = 0; i < 5; i++) {
            while (getline(myFile, line)) {
                str[i] = line;
                cout << "String [" << i << "] = " << str[i] << endl;
            }
        }
    }
}

【问题讨论】：

问问自己：当 i == 0 时读取了多少行？在调试器下运行程序，在str[i] = line 上设置断点，看看会发生什么。

标签： c++ arrays for-loop iteration getline

【解决方案1】：

我对您的代码进行了 2 次更改，以读取和打印文本文件的所有行（

1.注释掉for声明

2.在while循环中插入i++

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

int array[16], i;
fstream myFile;
string filename, line, str[256];

int main() {

    // 1. The user will enter the full name of the file
    cout << "Enter the file name to open: ";
    cin >> filename;
    getchar();  // clear the input buffer before reading the filename

    // 2. Open the file for reading (input)
    myFile.open(filename.c_str(), fstream::in);

    // only continue if the file has opened successfully
    if (myFile.is_open() == false) {
        cout << "ERROR: not able to open " << filename << endl;
    }
    else {
        // 3. Access the file - read all the lines from the file
        //for (i = 0; i < 5; i++) 
        {
            while (getline(myFile, line)) {
                str[i] = line;
                cout << "String [" << i << "] = " << str[i] << endl;
                i++;
            }
        }
    }
}

【讨论】：

【解决方案2】：

#include <iostream>
#include <fstream>
#include <string>
#include <vector>

// get used to not typing, using namespace

int main() 
{
    std::fstream myFile;
    std::string filename;
    std::string line;
    std::vector<std::string> lines; // use vector instead of arrays

    // error handling in C++, is exceptions
    myFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);

    // 1. The user will enter the full name of the file
    std::cout << "Enter the file name to open: ";
    std::cin >> filename;
    //getchar();  // clear the input buffer before reading the filename

    // 2. Open the file for reading (input)
    try
    {
        myFile.open(filename.c_str(), std::fstream::in);
    
        // 3. Access the file - read all the lines from the file
        int count = 0;
        while (getline(myFile, line))
        {
            lines.push_back(line);
            std::cout << "String [" << count++ << "] = " << line << std::endl;
        }
    }
    catch (const std::exception& e)
    {
        std::cout << "ERROR: not able to open " << filename << " error = " << e.what() << std::endl;
    }
}

【讨论】：