Question

I’m currently trying to write a program which will read words from a text file. Finally I plan to read certain words from a file and so on but at the moment I can’t get my current code to work.

I have 3 files. Header file, main file and implementation file.

ReadWords.h

#ifndef READWORDS_H
#define READWORDS_H
/**
* ReadWords class. Provides mechanisms to read a text file, and return
* capitalized words from that file.
*/
using namespace std;

#include <string>
#include <fstream>

 class ReadWords
 {
   public:
    /**
     * Constructor. Opens the file with the default name "text.txt".
     * Program exits with an error message if the file does not exist.
     */
     ReadWords();

    /**
     * Constructor. Opens the file with the given filename.
     * Program exits with an error message if the file does not exist.
     * @param filename - a C string naming the file to read.
     */
     ReadWords(char *filename);

    /**
     * Closes the file.
     */
     void close();


   // working storage.
   private:
     string nextword;
     ifstream wordfile;
     bool eoffound;

 };

 #endif

ReadWords.cpp

#include "ReadWords.h"
#include <iostream>
using namespace std;

//:: Defines function as member of class.


ReadWords::ReadWords(char *filename)
{
    ifstream str;
    str.open("hamlet.txt");
    char c;
    while ((c = str.get()) !=EOF){
        cout << c << endl;
    }
}

void close()
{

}

main.cpp

#include "ReadWords.h"

int main()
{
    ReadWords rw;
    rw.ReadWords("hamlet.txt");
}

Now I know I’m clearly doing something wrong, but I’m not 100% sure what.
The error I receive in compilation is as follows:

main.cpp: In function `int main()':
main.cpp:6: error: invalid use of `class ReadWords'

Tool completed with exit code 1

Any help is greatly appreciated. 🙂

Answer 1

In your main.cpp, you missed the quotes in the #include ReadWords.h directive. To fix this you should use #include "ReadWords.h".

Also, you should note that std::istream::get returns only a character. If you want to read a whole word in a (for example) std::string, you should use std::istream::operator >> like this:

std::ifstream in("my_file");
std::string word;

if (in.is_open()) {
    while (in >> word) {
        //do something with word
    }
}

Another thing that stands out is that in rw.ReadWords("hamlet.txt") you’re calling a constructor as if it were a member function. The proper way to use that overload is: ReadWords rw("hamlet.txt").

As a side note: the constructor’s job is to initialize the object. It’s not a good practice to do more than that inside it’s body.