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- - fstream problem.. (http://www.daniweb.com/forums/thread159046.html)

rumencho

Nov 23rd, 2008 6:11 am

fstream problem..

Hi all. I want to learn how to manipulate .txt files through C++ program. I want to be able to search trough chars in .txt file,sort them etc. I think the best way for this,should be,loading .txt file in char array and then manipulating the elements. but I don't know how..

#include <iostream.h>

#include <fstream.h>

#include <string.h>

int main()



{



               char array[100000];

        

        fstream ru ("c:\\ruru.txt",ios::out); 



        for (int i=0;i<10000;i++)

        

        {  ru << "rordo"; }  // write to file



                 array[ ] =ru  //obviously this doesn't work





return 0;

}

cikara21

Nov 23rd, 2008 8:46 am

Re: fstream problem..

Simple example..

Open a files,

while ch = getc(files)

{

  ary[i] = ch << 2;

  display ary[i]

}

twomers

Nov 23rd, 2008 10:01 am

Re: fstream problem..

You can do this quite elegantly with the STL... might be advanced, I dunno.

#include <fstream>

#include <vector>

#include <string>

#include <algorithm>



bool char_sort_function( char a, char b ) {

  return a>b;

}



int main( int argc, char *argv[] ) {



  // File contains: This is a test!

  std::ifstream in( "test.txt", std::ios::binary );



  if ( in ) {

    std::vector<char> vchar;



    // Read characters into vector 

    vchar.insert( vchar.end(), std::istream_iterator<char>(in), std::istream_iterator<char>() ); 



    // Sort them

    std::sort( vchar.begin(), vchar.end(), char_sort_function );



    // Prints characters

    std::copy( vchar.begin(), vchar.end(), std::ostream_iterator<char>(std::cout, "\n") );

  }



  return 0;

}

Edit: Note, this ignores whitespace.
Also change

#include <iostream.h>

#include <fstream.h>

#include <string.h>

#include <iostream>

#include <fstream>

#include <string>

ArkM	Nov 23rd, 2008 10:07 am

Re: fstream problem..

Sort chars? What for?!..
Can you explain what do you want to do with a file contents?

rumencho

Nov 23rd, 2008 10:13 am

Re: fstream problem..

]it doesn't work with getc, it says "getc- undeclared identifier" btw I'm using visual c++ compiler

I just want to take char from .txt file,and save it in char variable..or in array

I have also tried this way:

#include <iostream.h>

#include <fstream.h>



int main()

{ 

        fstream rufile ("c:\\ruru.txt",ios::in);

                char c;

        c= rufile.get (rufile,2);

        return 0;

}

but the compiler says thar it cannot convert parameter 2 from 'class fstream' to 'char *'

ArkM	Nov 23rd, 2008 10:58 am

Re: fstream problem..

Quote:

Originally Posted by rumencho (Post 742697)

#include <iostream.h>

#include <fstream.h>



int main()

{ 

        fstream rufile ("c:\\ruru.txt",ios::in);

                char c;

        c= rufile.get (rufile,2);

        return 0;

}

but the compiler says thar it cannot convert parameter 2 from 'class fstream' to 'char *'

The compiler said that it can't convert parameter 1 (first, not second)!

if (rufile.get(c)) {

    // OK, you get this char

} else {

    // end of file or i/o error

}

Set cursor on a function name and press F1. Look at the function prototype. Do you want ask daniweb for every new C++ function parameters?

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