如何将 .txt 文件中的文本读取到数组中？

Question

我想打开一个文本文件并完整读取它，同时使用 C++ 将其内容存储到变量和数组中。我的示例文本文件如下。 我想将第一行存储到一个整数变量中，将第二行存储到 3d 数组索引中，最后一行存储到字符串数组的 5 个元素中。

我知道如何打开文件进行阅读，但我还没有学会如何读取某些单词并将它们存储为整数或字符串类型。

3
2 3 3
4567 2939 2992 2222 0000

Answer 1

读取文本文件中的所有整数：

#include <fstream>

int main() {
    std::ifstream in;
    in.open("input_file.txt")
    // Fixed size array used to store the elements in the text file.
    // Change array type according to the type of the elements you want to read from the file
    int v[5];
    int element;

    if (in.is_open()) {
        int i = 0;
        while (in >> element) {
            v[i++] = element;
        }
    }

    in.close();

    return 0;
}

Answer 2

包括

fstream

：

#include <fstream>

并使用

ifstream

：

std::ifstream input( "filename.txt" );

能够逐行阅读：

for( std::string line; std::getline( input, line ); )
{
    //do what you want for each line input here
}

Answer 3

试试这个：

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

int main()
{
    std::ifstream file("filename.txt"); // enter the name of your file here

    int firstLine;

    int secondLine;
    const int X = 3;
    const int Y = 1;
    const int Z = 1;
    int ***arr3D;

    std::string myArray[5];
    std::string myString;

    if (file.is_open())
    {
        // store the first line into an integer variable
        file >> firstLine;

        // store the second line into a 3d array index
        arr3D = new int**[X];
        for (int i = 0; i < X; i++)
        {
            arr3D[i] = new int*[Y];

            for (int j = 0; j < Y; j++)
            {
                arr3D[i][j] = new int[Z];

                for (int k = 0; k < Z; k++)
                {
                    file >> secondLine;
                    arr3D[i][j][k] = secondLine;
                }
            }
        }

        // store the final line into 5 elements of a string array
        int i = 0;
        while (file >> myString)
        {
            myArray[i] = myString;
            i++;
        }
    }

    file.close();


    std::cout << firstLine << std::endl;

    for (int i = 0; i < X; i++)
    {
        for (int j = 0; j < Y; j++)
        {
            for (int k = 0; k < Z; k++)
            {
                std::cout << arr3D[i][j][k] << std::endl;
            }
        }
    }

    for (int i = 0; i < 5; i++)
    {
        std::cout << myArray[i] << std::endl;
    }

    return 0;
}