CStringFile Class

Environment: VC5/6, NT4, CE 2.11

Once upon a day I was asked to write an application which could do some serious filtering, on a ';' seperatedfile which held multiple collumns. The initial file was about 7 Mb in size, so I had to create a program which could read a file, process the read lines and produce a new output file.
So you think, what's the big deal ?
When I wrote that program, a pentium 133 was considered a fast PC. As far as I knew, there where no generic (Microsoft provided ??) solutions for a simple task as reading text from a file. So I build my own textfile reading class.
This brings me to the part which I found most interesting, the first version of this filtering program, did the job in several seconds.
So how come the thing worked so fast ? By the optimal manner of reading a text file.

The StringFile class itself consists of 2 loops. One loop is for filling a read buffer, and the other loop is used for reading a line from this buffer. The effect of these loops is that when the file is read, its is done by reading 2k of data per turn. Further processing (finding where any given line starts and when it stops) is done inside memory, not on disk. And, as you can probably known, memory is faster then disk...so there's my explanation for the speed of the filter program.
After some fiddling around with this class I decided to post this, so that everyone can enjoy this piece of code.

This sample show just how easy this thing works, open, read and close. What do you want more ??

#include "StringFile.h"

BOOL ReadTextFile(LPCSTR szFile)
{
 CStringFile 	sfText;
 CString		szLine;
 BOOL		bReturn = FALSE;	

 // When the given file can be opened
 if(sfText.Open(szFile)) 
 {
  // Read all the lines (one by one)
  while(sfText.GetNextLine(szLine)!=0)
  {
   printf("%s\r\n",szLine);	//And print them
  }
  sfText.Close(); // Close the opened file
  bReturn = TRUE; // And say where done succesfully
 }
 return bReturn;
}

Some benchmarking (trying to find optimum blocksize for reading) gave me the following results:

Blocksize Benchmark

This shows that the optimum size for this piece of code lies around 2k blocksize. Increasing this blocksize doesn't speedup reading, the only thing speeding up the read actions is probably improving the used code.

Downloads

Download source - 3 Kb


Comments

Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • Corporate e-Learning technology has a long and diverse pedigree. As far back as the 1980s, companies were adopting computer-based training to supplement traditional classroom activities. More recently, rich web-based applications have added streaming audio and video, real-time collaboration and other new tools to the e-Learning mix. At the same time, the growing availability of informal learning tools--a category that includes everything from web searches to social media posts--are having a major impact on …

  • Savvy enterprises are discovering that the cloud holds the power to transform IT processes and support business objectives. IT departments can use the cloud to redefine the continuum of development and operations—a process that is becoming known as DevOps. Download the Executive Brief DevOps: Why IT Operations Managers Should Care About the Cloud—prepared by Frost & Sullivan and sponsored by IBM—to learn how IBM SmartCloud Application services provide a robust platform that streamlines …

Most Popular Programming Stories

More for Developers

Latest Developer Headlines

RSS Feeds