How do I remove whitespace using the >> operator of ifstream?

I am trying to make a program that takes input from a .txt document and copies it to another .txt document. I understand that the >> operator of ifstream stops at each whitespace. Is there any way to set it so that it reads through the whitespace? For example, if I wanted to copy this sentence...

"This is a sentence I would like to copy."

from one .txt to another .txt, using >> would only copy the "This" string. Is there a way to make it read through the whitespace so it copies the entire sentence? Or do I have to tokenize the sentence in a loop using " " as my delimiter? Here is a watered down version of my code. Thanks.

Code:

---

#include <fstream>
#include <iostream>
#include <cstring>

using namespace std;

int main(){
   
  string str;
 
  ifstream inputFile ( "input.txt" );  //input.txt contains sentence I want to copy
  inputFile >> str;
  inputFile.close();
 
  ofstream outputFile ( "output.txt" );
  outputFile << str;
  outputFile.close();

  return 0;
}

---

http://www.cppreference.com/cppstring/getline.html

Thanks Tonto,

That works for whitespaces, is there anyway to make it read through the newline character, '\n' ? Now the >> operator stops at the end of each sentence. Thanks again.

> is there anyway to make it read through the newline character, '\n'
Well that depends. The fastest thing I can think of is to just read in two lines and concatenate them. If that's not good enough you would have to roll your own input function, which is a bit of work, but can be worth it.

How about this? all white space gets stored in the string via this
approach, as evidenced by the output.

Code:

---

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

using namespace std;

int main (void)
{
        string a_string;
        string dummy;
        char delim;
       
        ifstream a_file ("somefile.txt");
       
        if (!a_file.is_open ())
        {
                cerr << "Cannot open file!" << endl;
                return 1;
        }
       
        while (a_file >> dummy)
        {
                delim = a_file.get ();
                dummy += delim;
                a_string += dummy;
        }
       
        cout << a_string;
       
        return 0;
}

---

[UPDATE]
sorry, as Daved pointed out this is flawed, the best thing to do
would appear to be to read in one character at a time as
major_small suggests below
[/UPDATE]

I believe you can use the rd_buf of the input stream and send it to the output stream to get the whole thing at once. This will work with an output file stream and a stringstream which will get the whole file into a string.

Richie T's solution won't work if there are multiple whitespace characters in a row.

for things like this I usually just read in one char at a time...

Code:

---

#include <iostream>
#include <fstream>

int main()
{
        char ch;
       
        std::fstream in("test.in",std::ios::in);
        std::fstream out("test.out",std::ios::out|std::ios::trunc);

        while(in.get(ch))
        {
                out<<ch;
        }

        return 0;
}

---

Thanks for all your advice guys.

I ended up writing a function that read the string in a loop and concatamerizing each string into one large string which it would output to a file. I also added a parameter that set a "delimiting" string to tell the loop to stop.

Major_Small, that's a clever way of doing it. I think that would give me more options to control and edit the data. Hmmmmmm

BTW, I found the example. It is rdbuf, not rd_buf:

Code:

---

#include <iostream>
#include <fstream>
#include <sstream>

int main()
{
  std::ifstream file(__FILE__);
  std::ostringstream oss;
  if ( oss << file.rdbuf() )
      std::cout << oss.str();
}

---

Under what sort of circumstances under which oss << file.rdbuf() would fail?

An empty file? Or if the file doesn't exist since an error on open isn't checked.