如何在C ++中读取.txt文件

Question

We have this .txt that has this inside

PR-ATT-2 Sep 5 2018 Dec 15 2020
LE-GE-3 Oct 15 2019 Jan 20 2021

With our code, we're trying to set the first line to a string

#include <string>
#include <array>
#include <cstdlib>
#include <fstream>
#include <istream>
#include <iostream>

using namespace std;

int main(int argc, char* argv[]) {
    ifstream projin;
        projin.open(argv[1], ios::in);
        // Making sure the file opened correctly
        if ((projin.is_open()) == false) {
            cout << "There was an error opening the file";
            return 1;
        } else {
            string projectline;
            getline(projin, projectline);
            cout << projectline << " ";
            projin.close();
            return 2;
        }
    return 0;
}

This returns nothing. But if the code looks like this

#include <string>
#include <array>
#include <cstdlib>
#include <fstream>
#include <istream>
#include <iostream>

using namespace std;

int main(int argc, char* argv[]) {
    ifstream projin;
        projin.open(argv[1], ios::in);
        // Making sure the file opened correctly
        if ((projin.is_open()) == false) {
            cout << "There was an error opening the file";
            return 1;
        } else {
            string projectline;
            getline(projin, projectline);
            cout << "Hello my name is Alejandro, and my favorite word is 
pneumonoultramicroscopicsilicovolcanoconiosis " << projectline << " ";
            projin.close();
            return 2;
        }
    return 0;
}

This returns "Hello my name is Alejandro, and my favorite word is pneumonoultramicroscopicsilicovolcanoconiosis PR-ATT-2 Sep 5 2018 D".

We can not figure out for the life of us what is going on.

Answer 1

We changed it to a while loop that prints the line until the end of the file, and that gave us our intended output.

ifstream projin;
projin.open(argv[1], ios::in);
// Making sure the file opened correctly
if ((projin.is_open()) == false) {
    cout << "There was an error opening the file";
    return 1;
} else {
    string projectline;
    while (getline(projin, projectline)) {
        cout << projectline << endl;
    }
    projin.close();
    return 2;
}