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Nov 23rd, 2008

fstream problem..

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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..

(Toggle Plain Text)

#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;
}

Last edited by rumencho; Nov 23rd, 2008 at 6:12 am.

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rumencho

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Newbie Poster

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Nov 23rd, 2008

Re: fstream problem..

Simple example..

C++ Syntax (Toggle Plain Text)
Open a files,
while ch = getc(files)
{
  ary[i] = ch << 2;
  display ary[i]
}
Open a files,
while ch = getc(files)
{
  ary[i] = ch << 2;
  display ary[i]
}

cikara21

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Posting Whiz

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since Jul 2008

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Nov 23rd, 2008

Re: fstream problem..

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

cpp Syntax (Toggle Plain Text)
#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;
}
#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

C++ Syntax (Toggle Plain Text)
#include <iostream.h>
#include <fstream.h>
#include <string.h>
#include <iostream.h>
#include <fstream.h>
#include <string.h>

C++ Syntax (Toggle Plain Text)
#include <iostream>
#include <fstream>
#include <string>
#include <iostream>
#include <fstream>
#include <string>

Last edited by twomers; Nov 23rd, 2008 at 10:03 am.

twomers

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Posting Virtuoso

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Nov 23rd, 2008

Re: fstream problem..

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

ArkM

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Postaholic

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Nov 23rd, 2008

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:

(Toggle Plain Text)

#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 *'

Last edited by rumencho; Nov 23rd, 2008 at 10:22 am.

rumencho

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Nov 23rd, 2008

Re: fstream problem..

Click to Expand / Collapse Quote originally posted by rumencho ...

]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:
(Toggle Plain Text)
#include <iostream.h>
#include <fstream.h>

int main()
{ 
	fstream rufile ("c:\\ruru.txt",ios::in);
		char c;
	c= rufile.get (rufile,2);
	return 0;
}
#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)!

C++ Syntax (Toggle Plain Text)
if (rufile.get(c)) {
    // OK, you get this char
} else {
    // end of file or i/o error
}
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?

ArkM

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