多行标准输入-C ++ [英] Multi-line stdin - C++

问题描述

因此，如果我有一个采用stdin之类的程序，例如

So if i have a program that takes stdin such as

1
5
2
4

我该如何精确地说出每一行并打印出该值，这就是我的想法:

How exactly can i go through each line and say print that value, This is what im thinking:

#include <iostream>
using namespace std;

int main()
{

  while ( // input has ended// ) {
  cout << //current line//

  //increment to next line//

 }     

  return 0;
}

有没有办法?

推荐答案

我喜欢的模式是:

while (!cin.eof())
{
    string line;
    getline(cin, line);

    if (cin.fail())
    {
        //error
        break;
    }

    cout << line << endl;
}

与其他答案一样，您可以键入 CTRL + Z 将 EOF 发送到 STDIN .如果 STDIN 是管道，则当流中没有更多数据时，将发送 EOF .

As in the other answers, you can type CTRL+Z to send an EOF to STDIN. If STDIN is a pipe, then EOF will be sent when the stream has no more data.

要保存到向量中:

vector<int> numbers;

while (!cin.eof())
{
    string line;
    getline(cin, line);

    if (cin.fail())
    {
        //error
        break;
    }

    cout << line << endl;

    istringstream iss(line);
    int num;
    iss >> num;
    numbers.push_back(num);
}

如果您想要C样式的数组(尽管我会推荐 std :: vector :

If you want a C-style array (although I would recommend std::vector:

size_t START_SIZE = 100;

size_t current_size = START_SIZE;
size_t current_index = 0;

int* numbers = new int[current_size];

while (!cin.eof())
{
    string line;
    getline(cin, line);

    if (cin.fail())
    {
        //error
        break;
    }

    cout << line << endl;

    if (current_index == current_size)
    {
        current_size += START_SIZE;
        int* tmp_arr = new int[current_size];

        for (size_t count = 0; count < current_index; count++)
        {
            tmp_arr[count] = numbers[count];
        }

        delete [] numbers;
        numbers = tmp_arr;
    }

    istringstream iss(line);
    int num;
    iss >> num;

    numbers[current_index] = num;
    current_index++;
}

delete [] numbers;

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