CCmdLine - A command line parser

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Introduction

Parsing command lines with the standard C string functions (strlen, strcpy, etc.) or even with the CString operators is a nightmare. But, CCmdLine makes it effortless.

CCmdLine was written for use with console apps, but can be easily used in any application which requires command-line parsing.

CCmdLine uses STL for its collection classes, so it works in both MFC and non-MFC apps. If you are using this in an MFC app, the switches and arguments will be returned as 'CString's. If you are using this in a non-MFC app, they will be returned as STL 'string's.

CCmdLine is a simple way to parse a command line into switches and arguments. Example :

MyApp.exe -sw1 arg1 arg2 -sw2 arg3 -sw3 -sw4

When using CCmdLine, "-sw1", "-sw2", "-sw3" and "-sw4" are switches and "arg1", "arg2" and "arg3" are arguments.

Example:

Assume the application we're writing uses a command line that has two required switches and two optional switches. The app should abort if the required switches are not present and continue with default values if the optional switches are not present.

Sample command line :

MyApp.exe -p1 text1 text2 -p2 "this is a big argument" -opt1 -55 -opt2

Switches -p1 and -p2 are required.

p1 has two arguments and p2 has one.

Switches -opt1 and -opt2 are optional.

opt1 requires a numeric argument.

opt2 has no arguments.

Also, assume that the app displays a 'help' screen if the '-h' switch is present on the command line.

Example

Here's how you can use CCmdLine to handle the command line processing:

// if this is an MFC app, un-comment the next line
// #include "stdafx.h"

#include "CmdLine.h"

void main(int argc, char **argv)
{
  // our cmd line parser object
  CCmdLine cmdLine;

  // parse the command line.
  // in MFC apps, use __argc and __argv here
  if (cmdLine.SplitLine(argc, argv) < 1)
  {
     // no switches were given on the command line, abort
     ASSERT(0);
     exit(-1);
  }

  // test for the 'help' case
  if (cmdLine.HasSwitch("-h"))
  {
     show_help();
     exit(0);
  }

  // StringType is defined in CmdLine.h.
  // it is CString when using MFC, else STL's 'string'
  StringType p1_1, p1_2, p2_1;

  // get the required arguments
  try
  {
     // if any of these GetArgument calls fail,
     // we'll end up in the catch() block

     // get the first -p1 argument (arg number '0')
     p1_1 = cmdLine.GetArgument("-p1", 0);

     // get the second -p1 argument (arg number '1')
     p1_2 = cmdLine.GetArgument("-p1", 1);

     // get the first -p2 argument
     p2_1 = cmdLine.GetArgument("-p2", 0);

  }
  catch (...)
  {
     // one of the required arguments was missing, abort
     ASSERT(0);
     exit(-1);
  }

  // get the optional parameters

  // the GetSafeArgument member does not throw exceptions, and
  // allows for the use of a default value, if the switch is not found.

  // get the argument, convert it to an int.
  // default to '100', if the argument was not found
  int iOpt1Val =    atoi( cmdLine.GetSafeArgument( "-opt1", 0, 100 ) );

  // since opt2 has no arguments, just test for the presence of
  // the '-opt2' switch
  bool bOptSwitch2 =   cmdLine.HasSwitch("-opt2");

  .... and so on....

}

Pretty simple stuff...

History

• 31 Jan 2002 - Updated source.
• 25 Aug 2011 - Updated source.