Store contents of file into variable

[chgifts]

Hello, I am new to c++ and honestly never use it, but I need to write a little script that takes that contents of a file and stores it into a variable.

With that variable(string) I need to create 2 more variables with a substring command. Then I need to write those 2 variabless to the lpt1 printer port.

I currently have this

#include <stdio.h>

void main(void)
{
FILE *fp;
char ch;

fp = fopen(&quot;test.txt&quot;,&quot;r&quot;
ch = getc(fp);
while(ch!=EOF)
{
putchar(ch);
ch = getc(fp);
}
}

but not sure how to get a substring out of the variable.
I am trying to get out characters 16-24 and 34-52 out of the variable and store them into 2 speperate variable and then write those 2 variable to the lpt1 printer port. I hope this makes sense.

 

[globos]

OK, here is some C++ code that read an input file, stores it inside a string object and extract 2 substrings :

#include <iostream>
#include <string>
#include <fstream>
#include <assert.h>
using namespace std;

int main (int argc, char** argv)
{
  if (argc == 2)
    {
      ifstream in (argv[1]);
      assert (in.is_open ());//in_file_open

      in >> noskipws;//do_not_skip_white_space_while_reading_stream      
      string buffer;//store_contents_of_input_file

      while (!in.eof ())
	{
	  char read_char;
	  in >> read_char;
	  buffer += read_char;
	}

      assert (buffer.size () > 24);//correct_size_before_sub_extraction
      string sub1 = buffer.substr (16, 24 - 16);
      assert (buffer.size () > 52);//correct_size_before_sub_extraction
      string sub2 = buffer.substr (34, 52 - 34);

      cout << &quot;sub1 : &quot; << sub1 << endl;
      cout << &quot;sub2 : &quot; << sub2 << endl;
    }

}

This code reads white space chars(\n, etc.) too, if you want to do not, replace :

in >> noskipws;

by

in >> skipws

Or maybe simply remove this line.


--
Globos

 

[globos]

Oups, sorrry, I forgot the main's body last line :

return 0;

--
Globos