Strings comparison

[mtweeman]

Hi,

I'm working on a Win app that opens another Win app with additional arguments.
The thing is that I don't want a user to be able to open the 2nd one without turning on the 1st one. It should always be opened by app 1. Therefore, app 1 passes some string (password) as an argument to app 2. In app 2 there is comparison between two strings, but for some reason they are seen to be "not equal".

In 2nd app I use following piece of code to compare these two strings:

LPWSTR *szArgList;
  int argCount;
  wchar_t my_pass[] = L"12345678\0";

  szArgList = CommandLineToArgvW(GetCommandLine(), &argCount);

  //file
  std::ofstream out("output.txt");
  out << wcscmp(my_pass, szArgList[2]);
  out.close();
  //file 

I thought that in the output file I'll see 0 as a result, but I got 1. Do you have an idea what I'm doing wrong?

[Thomas1965]

Since you use wchar_t you also need to use wofstream.

[48bpfSEw]

L"12345678\0"

The "\0" in your string is not required since a string in CPP has allready an \0 at the end.

[Naughty Albatross]

> Since you use wchar_t you also need to use wofstream.
No, the OP is trying to print out the result of the function wcscmp(). He was not trying to print out any wchar_t string.

[Thomas1965]

Why don't you print the args your program is receiving ?
https://msdn.microsoft.com/en-us/library/windows/desktop/bb776391(v=vs.85).aspx

[mtweeman]

Thanks for comprehensive replies.

Necip, thanks for suggestion, I already removed "\0". You are totally correct here.

Thomas1965, indeed I was not printing any wchar_t string. However, I tried your advice and the problem is actually there. In txt file I got:

args: 14
App1 argument 0: G:\bin\cefsimple.exe
App1 argument 1: --type=renderer
App1 argument 2: --no-sandbox
App1 argument 3: --disable-databases
App1 argument 4: --lang=en-US
App1 argument 5: --lang=en-US
App1 argument 6: --log-file=G:\bin\debug.log
App1 argument 7: --device-scale-factor=1
App1 argument 8: --num-raster-threads=2
App1 argument 9: --content-image-texture-target=3553,3553,3553,3553,3553,3553,3553,3553,3553,3553,3553,3553,3553,3553
App1 argument 10: --video-image-texture-target=3553
App1 argument 11: --disable-accelerated-video-decode
App1 argument 12: --channel=7076.1.1397704486\1723621388
App1 argument 13: /prefetch:673131151

As I was using App1 to open App2 which was Chromium open-source version for developers, i.e. CEF (Chromium Embedded Framework), it passed also some arguments I wasn't aware of.

Now the question is: am I able to send some arguments on certain position in command line? Argument 14 (or maybe I should say 15 as we're counting from 0) seems to be first one available.

[Duthomhas]

In general you should not expect command-line arguments to be in any particular order. (If you do, your program will break when the calling program changes its output!)

Find the argument you wish to handle.

  int argCount;
  LPWSTR *szArgList = CommandLineToArgvW(GetCommandLine(), &argCount);
  if (!szArgList)
  {
    ...
  }

  std::u16string tag = "/prefetch:";
  std::u16string pwd;
  for (int n = 1; n < argCount; n++)
    if (std::u16string( szArgList[ n ] ).compare( 0, tag.size(), tag ) == 0)
    {
      pwd = szArgList[ n ] + tag.size();
      break;
    }
  if (pwd.empty())
  {
    ...
  }

  //use pwd 

Hope this helps.

[mtweeman]

Duoas, thanks for advice. I'll follow it.

In the end, it was the problem of the architecture of 2nd app (CEF) as I mentioned earlier. I was getting arguments of incorrect part of the program, i.e. renderer, instead of browser itself. After reorganizing some part of code I got proper arguments that I actually was passing from the 1st app.

Thanks for your help. Couldn't make it without help of all of you.