c++ - How to read a file line by line or a whole text file at once?

Question

I'm in a tutorial which introduces files (how to read from file and write to file)

First of all, this is not a homework, this is just general help I'm seeking.

I know how to read one word at a time, but I don't know how to read one line at a time, or how to read the whole text file.

What if my file contains 1000 words? It is not practical to read entire file word after word.

My text file named "Read" contains the following:

I love to play games
I love reading
I have 2 books

This is what I have accomplished so far:

#include <iostream>
#include <fstream>

using namespace std;
int main (){
   
  ifstream inFile;
  inFile.open("Read.txt");

  inFile >>

Is there any possible way to read the whole file at once, instead of reading each line or each word separately?

Answer 1

You can use std::getline :

#include <fstream>
#include <string>

int main() 
{ 
    std::ifstream file("Read.txt");
    std::string str; 
    while (std::getline(file, str))
    {
        // Process str
    }
}

Also note that it's better you just construct the file stream with the file names in it's constructor rather than explicitly opening (same goes for closing, just let the destructor do the work).

Further documentation about std::string::getline() can be read at CPP Reference.

Probably the easiest way to read a whole text file is just to concatenate those retrieved lines.

std::ifstream file("Read.txt");
std::string str;
std::string file_contents;
while (std::getline(file, str))
{
  file_contents += str;
  file_contents.push_back('
');
}