Read/Write Plobrem with C++

[stealwings]

Hello everyone,
I'm kind of dummy in this thing of programing but I have to do it so. Well I have this problem; I wrote a read and write program, it reads the file well but when it writes is it only writes the last word of the opened file and in a infinite loop, I have close the file though. Plzz can some one help me? My code is like this:

#include "stdafx.h"
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include <cstdlib>
#include <vector>
#include "code.h"
#include "FileManip.h"
#define MAXLENGTH 256
int main(int argc, char* argv[])
{
    char GetWord[MAXLENGTH];
    ifstream OpenFile;
    ofstream WriteFile;
    OpenFile.open("myfile.txt", ios::in);
    if(!OpenFile)
    {
        cerr<<"File not found!"<<endl;
        exit(1);
    }
    OpenFile>>GetWord;
    cout<<GetWord<<endl;
    while (!OpenFile.eof())
    {
        OpenFile>>GetWord;
        cout<<GetWord<<endl;
    }
    OpenFile.close();
    cout<<"End of file reached!"<<endl;
    char *MyString;
    WriteFile.open("myfile.dat", ios::out);
    if(!WriteFile)
    {
        cerr<<"Couldn't create file."<<endl;
        exit(1);
    }
    MyString=GetWord;
    WriteFile<<MyString;
    while(OpenFile)
    {
        WriteFile<<MyString;
    }
    WriteFile.close();
    return 0;
}

thanks in advance!

[AdrianH]

Hi,

I had a bit of trouble trying to get your file to compile. You have a bunch of extraneous includes, and is probably the reason that you got it to compile, although badly.

Given the first include, it looks like you are using MS VC++. Considering that you did not use a ‘using namespace std;’ line, it is either in your other files that you included (which is bad BTW, never have a using namespace in anything but a source file, otherwise you will eventually have strange clashes occurring) or you have got one really old compiler.

#include "stdafx.h"
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
//#include <cstdlib>
//#include <vector>
//#include "code.h"
//#include "FileManip.h"
#include<fstream>
#include<iostream>
 
using namespace std;
 

Commenting out the extraneous header files and inserting in the relevant ones and the using namespace statement, I was able to compile your program. Good news is that reading section works… almost.

Here is a website that has all the C++ standard library documents: http://www.cplusplus.com/reference/iostream/ifstream/

Instead of using the >> operator to fill your array, use the getline function. Try with what you got and then try with the getline function and you will see what I mean. >> to a char array reads in words but you never see the whitespaces.

You shouldn’t need the extra file read and output just before the loop. It will be handled within the loop.

The reason that you were getting the last word repeated in an infinite loop is because by the time you got to that section of the code:

1. you were outputting the last word you had read in, since by this time you had read in every ‘word’ in the file in your first loop, which was the last word of the file
2. you were using OpenFile as if it had a Boolean value. Well it is not, even though you can use the ! operator on it, without the ! operator I’m not even sure what it means. You probably mean to use the fail function, and not on OpenFile but on WriteFile.

Remember, you can read from a file and write to another in the same loop. You are already doing that with cout, so why not open your WriteFile after you open your OpenFile and write the line right after you read it as you are doing with cout.


Hope this helps.


Adrian

PS If you see a message from me before this, disregard it. I tried to delete it.

[stealwings]

Hi,

I had a bit of trouble trying to get your file to compile. You have a bunch of extraneous includes, and is probably the reason that you got it to compile, although badly.

Given the first include, it looks like you are using MS VC++. Considering that you did not use a ‘using namespace std;’ line, it is either in your other files that you included (which is bad BTW, never have a using namespace in anything but a source file, otherwise you will eventually have strange clashes occurring) or you have got one really old compiler.

#include "stdafx.h"
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
//#include <cstdlib>
//#include <vector>
//#include "code.h"
//#include "FileManip.h"
#include<fstream>
#include<iostream>
 
using namespace std;
 

Commenting out the extraneous header files and inserting in the relevant ones and the using namespace statement, I was able to compile your program. Good news is that reading section works… almost.

Here is a website that has all the C++ standard library documents: http://www.cplusplus.com/reference/iostream/ifstream/

Instead of using the >> operator to fill your array, use the getline function. Try with what you got and then try with the getline function and you will see what I mean. >> to a char array reads in words but you never see the whitespaces.

You shouldn’t need the extra file read and output just before the loop. It will be handled within the loop.

The reason that you were getting the last word repeated in an infinite loop is because by the time you got to that section of the code:

1. you were outputting the last word you had read in, since by this time you had read in every ‘word’ in the file in your first loop, which was the last word of the file
2. you were using OpenFile as if it had a Boolean value. Well it is not, even though you can use the ! operator on it, without the ! operator I’m not even sure what it means. You probably mean to use the fail function, and not on OpenFile but on WriteFile.

Remember, you can read from a file and write to another in the same loop. You are already doing that with cout, so why not open your WriteFile after you open your OpenFile and write the line right after you read it as you are doing with cout.


Hope this helps.


Adrian

PS If you see a message from me before this, disregard it. I tried to delete it.

Thx a lot, the strange header you were talking about "FileManip.h" (in which I included fstream, std:: ifstream and std:: ofstream and well <iostream> and using namespace std; as well). and "Code.h" (which is for a table structure, I'n not using yet) are two of the headers I made sorry for forgot to put that detail, and now I understand a little why I get the infinite loop, so I can't separate the loop for GetWord and WriteFile? I was only using cout so I could see that my GetWord function was working properly. So now the answer to my question is that I should put my WriteFile function into the same loop as my GetWord function so they can work properly? Thanks a lot, I will try.

[AdrianH]

Thx a lot, the strange header you were talking about "FileManip.h" (in which I included fstream, std:: ifstream and std:: ofstream and well <iostream> and using namespace std; as well). and "Code.h" (which is for a table structure, I'n not using yet) are two of the headers I made sorry for forgot to put that detail, and now I understand a little why I get the infinite loop, so I can't separate the loop for GetWord and WriteFile? I was only using cout so I could see that my GetWord function was working properly. So now the answer to my question is that I should put my WriteFile function into the same loop as my GetWord function so they can work properly? Thanks a lot, I will try.

If you want to separate the Reading from the Writing, you are going to have to either read in the entire file into memory (usually not a preferred choice) or use a class to maintain the read stream and write stream. That way you can create an outer loop from the class that does the read function and a write function, but then you have just gone back to putting the read and write calls into the same loop. So yes, put the read and write in the same loop.

Glad to help.


Adrian