Detect new line c++ fstream

Question

How do I read a .txt copy the content to another .txt by using fstream to a similar content. The problem is, when in the file there is new line. How do I detect that while using ifstream?

user enter "apple"

Eg: note.txt => I bought an apple yesterday. The apple tastes delicious.

note_new.txt => I bought an yesterday. tastes delicious.

the resulting note suppose to be above, but instead: note_new.txt => I bought an yesterday. tastes delicious.

How do I check if there is a new line in the source file, it also will create new line in new file.

Here is my current code:

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

using namespace std;

int main() {
    ifstream inFile ("note.txt");
    string word;
    ofstream outFile("note_new.txt");

    while(inFile >> word) {
        outfile << word << " ";
    }
}

can you all help me? actually I also check when the word retrieved is the same as what user specified, then I won't write that word in the new file. So it general, it will delete words which are the same as the one specified by user.

Answer 1

Line-by-line method

If you still want to do it line-by-line, you can use std::getline() :

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

using namespace std;

int main() {
    ifstream inFile ("note.txt");
    string line;
    //     ^^^^
    ofstream outFile("note_new.txt");

    while( getline(inFile, line) ) {
    //     ^^^^^^^^^^^^^^^^^^^^^
        outfile << line << endl;
    }
}

It gets a line from the stream and you just to rewrite it wherever you want.

---

Easier method

If you just want to rewrite one file inside the other one, use rdbuf :

#include <fstream>

using namespace std;

int main() {
    ifstream inFile ("note.txt");
    ofstream outFile("note_new.txt");

    outFile << inFile.rdbuf();
//  ^^^^^^^^^^^^^^^^^^^^^^^^^^
}

---

EDIT : It will permit to remove the words you don't want to be in the new file :

We use std::stringstream :

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

using namespace std;

int main() {
    ifstream inFile ("note.txt");
    string line;
    string wordEntered("apple"); // Get it from the command line
    ofstream outFile("note_new.txt");

    while( getline(inFile, line) ) {

        stringstream ls( line );
        string word;

        while(ls >> word)
        {
            if (word != wordEntered)
            {
                 outFile << word;
            }
        }
        outFile << endl;
    }
}