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parsing commandline arguments of WinMain

Posted on 2006-11-29
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Last Modified: 2008-01-09
Hi all,

I wanted a simple, failsafe way to get command line arguments from:

int PASCAL WinMain( HINSTANCE hInst, HINSTANCE hPrevInst, LPSTR  lpCmdLine,
    int nCmdShow );

The arguments are 2 absolute file-paths and spaces(blanks) can be part of the file-paths. So, I cann't just search for blank space to find out the next token :)

thanks,
Vikram


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Question by:Vikram_B
8 Comments
 
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Expert Comment

by:AlexFM
ID: 18035691
If argument contains blanks, client must use "" for such argument:

yourProgram "C:\Program Files\Dir\File1.txt" "C:\Program Files\Dir\File2.txt"

This is general rule for all command parsers. Without this there is no way to detect number of parameters.
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Expert Comment

by:Infinity08
ID: 18035699
The norm is to enclose the file paths with "" - for example :

    command "/path/to first/file 1" "/path/to second/file 2"

Those will be passed as :

    argument 1 : /path/to first/file 1
    argument 2 : /path/to second/file 2
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Author Comment

by:Vikram_B
ID: 18035746
thanks Infinity08,

But, how to parse argument1 and argument2? can I use some string manipulation function?
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LVL 53

Expert Comment

by:Infinity08
ID: 18036154
You can use whatever you want, but this is the basic idea :

    char *cmdLine = (char*) lpCmdLine;
    char args[128][128] = { 0 };
    int i = 0;
    while (*cmdLine) {
      if (*cmdLine == ' ') {
        cmdLine++;
      }
      else {
        char *end = 0;
        if (*cmdLine == '\"') {
          cmdLine++;
          end = strchr(cmdLine, '\"');
        }
        else {
          end = strchr(cmdLine, ' ');
        }
        if (end) {
          strncpy(args[i], cmdLine, end - cmdLine);
          args[i][end - cmdLine] = '\0';
          cmdLine = end + 1;
          i++;
        }
        else {
          /* ERROR - treat it !! */
        }
      }
    }

Note that this is just for you to get an idea of how you COULD do it. This is ny no means complete code !!!
If more than 128 args are passed or if one arg is more than 127 characters long, this code will create problems !!
The above code is not validated, and is just written off the top of my head, so there might still be other problems with it !
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Expert Comment

by:Infinity08
ID: 18036159
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Expert Comment

by:itsmeandnobodyelse
ID: 18038022
Maybe you want that (it is tested):

#include <string>
#include <vector>
using namespace std;

int parseCmdLine(const char* szcmdline, vector<string> arguments)
{
    string cmdline = szcmdline;
    cmdline += ' ';   // add a final space for easier parsing
    bool bQuotes = false;
    int lpos = 0;
    int i = 0;
    for (i = 0; i < cmdline.length(); ++i)
    {
          char c = cmdline[i];
          switch(c)
          {
          case '"':   // note it is  '  "  '
                bQuotes = !bQuotes;   break;
          case ' ':
                if (bQuotes)
                     break;   // ignore space if within quotes
                if (i > lpos)
                     arguments.push_back(cmdline.substr(lpos, i - lpos));
                lpos = i+1;
          }
    }
    return arguments.size();
}

You can use it in your WinMain like

    vector<string> arguments;
    int nArgs = parseCmdLine( lpCmdLine, arguments );

    for (int i = 0; i < nArgs; ++i)
          cout << arguments[i] <<  endl;

Regards, Alex



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Accepted Solution

by:
wayside earned 25 total points
ID: 18039182
What might be easier if you are using the Microsoft compiler, is that argc and argv are available as globals. The globals are __argc and __argv (that's two underscore characters in front).

Then you don't have to parse at all:

int APIENTRY _tWinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPTSTR    lpCmdLine,
                     int       nCmdShow)
{
  char buffer[500];
  for (int i=0; i<__argc; i++) {
    sprintf(buffer, "arg %ld = %s", i, __argv[i]);
    MessageBox(NULL, buffer, "cmdline", MB_OK);
  }
}

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Author Comment

by:Vikram_B
ID: 18052583
thanks everyone!
 sorry, i cudnt reply in time. i donno why, but i am not receiving notifications from ee for the new comments posted!
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