Re: help old VBasic programmer with simple file read , Please :)

From:

Rolf Magnus <ramagnus@t-online.de>

Newsgroups:

comp.lang.c++

Date:

Thu, 14 Jun 2007 06:30:27 +0200

Message-ID:

<f4qg94$qt$00$1@news.t-online.com>

marks542004@yahoo.com wrote:

Hi all ,

I am an old programmer now hobbyist who has used cobol, basic, and
RPG .
I am new to c++ but have Microsoft Visual Studio 6.0.

That compiler is very out-dated. It was released before C++ was
standardized.

I have a program in Basic that reads a file , looks for lines
containing a specific string , and lists them.

I am trying to do the same thing in C in a search for speed with very
large files.

I have a program working until I try testing for the substring.

heres the code I have:

// stimquick.cpp : Defines the entry point for the console
application.
//

#include "stdafx.h"

Even through its name starts with "std", it is a non-standard header. It's
not needed for your program.

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

char str[] = "Geom";

int main(int argc, char* argv[])
{
  string line;
  char *pdest;
  ifstream myfile ("C:\\Documents and Settings\\Owner\\My Documents\
\downloads\\stimuli\\stimV4wall2.pz2");
  if (myfile.is_open())
  {
    while (! myfile.eof() )

This loop is incorrect. See question 15.5 in the "C++ FAQ lite".

{
getline (myfile,line);
pdest = strstr( line, str );

Why aren't you using std::string::find?

if( pdest != NULL )
cout << line << endl;
    }
    myfile.close();
  }

  else cout << "Unable to open file";

  return 0;
}

When you stop laughing :) can anyone tell me WHY I get an error about
not being able to convert between types in the strstr step.

Because strstr expects a pointer to const char, but you gave it an object of
class std::string.

I suspect I am using the wrong project type as well for what I
eventually want to do.

Either use line.c_str() as first argument to strstr or use something like
line.find(str) instead of strstr.

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