Programming Forums > Application Development > C++

jayme · May 6th, 2006, 10:09 AM

I'm trying to create a small(very small) task manager. The processes are being seen properly and I can print the names of the processes to the screen, but I'm having a problem with the new task portion. Here's a bit of code.

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for(;;)
    {
        if ( !EnumProcesses( aProcesses, sizeof(aProcesses), &cbNeeded ) )
        return 1;

        // Calculate how many process identifiers were returned.

        cProcesses = cbNeeded / sizeof(DWORD);

        // Print the name and process identifier for each process.

        for ( i = 0; i < cProcesses; i++ ){
        PrintProcessNameAndID( aProcesses[i] );
        strcpy(name, szProcessName);
        MessageBox(NULL, name, szProcessName,NULL);
        vec.push_back(*name);
        }
        
      /* Here's the more important code that's having problems */
        for(i = 0; i <= vec.size(); i++){
            ne=vec.at(i);
            if(ne=="notepad.exe"){ //If data in location is == to taskmgr.exe
            // do nothing since the program's already running
            break;
            }
            else

            if(vec.back()){ // If we're at the end of the vector and no notepad.exe was found...
                ShellExecute(NULL, "open", "notepad.exe", NULL, NULL, SW_SHOW); //open notepad.exe
                break;
            }
        }
    }

The problem I'm having is that "if(ne=="notepad.exe")" acts as if it's not even there. When I loop through the process list and create a messagebox displaying each process running, it will display that notepad.exe is running, but it still ends up opening another instance of the notepad. It's most likely just a small problem since I just woke up, but does anyone see anything suspicious?

By the way, the "ne" string is declared as string ne;, not a character array.

grumpy · May 6th, 2006, 10:20 AM

Your problem has nothing to do with string comparisons; the basic logic is wrong. The test of "if (vec.back())" is within the for loop. Which has the effect that, if the first entry in vec is not "notepad.exe", then notepad is launched. Thanks to the "break" statements your code will only ever look at the first entry in vec as well.

If the entries in vec are obtained from the system, there may also be some path information (eg notepad.exe might be something like "C:\\WINNT\\notepad.exe").

Seif · May 6th, 2006, 10:23 AM

try if (strcmp(ne, notepad.exe) == 0)

InfoGeek · May 6th, 2006, 10:28 AM

Quote:

Originally Posted by jayme

By the way, the "ne" string is declared as string ne;, not a character array.

Quote:

Originally Posted by seif

try if (strcmp(ne, notepad.exe) == 0)

Seif · May 6th, 2006, 10:34 AM

forgot the ""'s sorry.

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if (strcmp(ne, "notepad.exe") == 0)

InfoGeek · May 6th, 2006, 10:39 AM

What? Are you reading the posts?

Ooble · May 6th, 2006, 10:40 AM

Seif, you're missing the point. strcmp is used to compare character arrays (char*). Jayme is using the C++ string type, std::string.

Seif · May 6th, 2006, 11:45 AM

yeah my bad. have a massive hangover and didnt really read post properly or take a good look at the code. sorta just took a quick scim n see if there was any suggestions i could do to help. sorry.

just read the final line... what a dumbass i am lol.

jayme · May 6th, 2006, 12:31 PM

I've decided I don't need vectors, but still, I can't seem to figure out why this isn't working, since it's more simple than using vectors. It almost seems too simple to even come across a problem, but hmm.

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for ( i = 0; i < cProcesses; i++ ){
        PrintProcessNameAndID( aProcesses[i] );
        name = szProcessName;
        MessageBox(NULL, name.c_str(), szProcessName,NULL);

        if(i==cProcesses) p=0;
        if(name=="taskmgr.exe"){
        p=1;
        continue;
        }
        else
        if(name!="taskmgr.exe" && i==cProcesses && p==0)
            ShellExecute(NULL, "open", "notepad.exe", NULL, NULL, SW_SHOW);
        }

This looks like it should work, but notepad doesn't run at all with this code, wether taskmgr.exe is open or not.

Cache · May 6th, 2006, 6:38 PM

I'd suggets using vectors, again. Then you can make use of iterators and algorithms. Assuming I'm following this thread right, I think this should do the trick:
( requires #include <algorithm> )

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std::vector<char*>::const_iterator it = find( vec.begin(), vec.end(), "taskmgr.exe" );

if ( it != vec.end() ) 
{ 
	::ShellExecute( NULL, "open", "notepad.exe", NULL, NULL, SW_SHOW );
}

Just the change the type in the vector if you're not using char*.

May 6th, 2006, 10:34 AM	#5
Seif Hobbyist Programmer Join Date: Jan 2006 Location: UK Posts: 242 Rep Power: 3	forgot the ""'s sorry. (Toggle Plain Text) if (strcmp(ne, "notepad.exe") == 0) if (strcmp(ne, "notepad.exe") == 0)

May 6th, 2006, 10:39 AM	#6
InfoGeek Professional Programmer Join Date: Jun 2005 Location: India, The great. Posts: 435 Rep Power: 4	What? Are you reading the posts? __________________ PFO - My daily dose of technology.

May 6th, 2006, 10:40 AM	#7
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,434 Rep Power: 9	Seif, you're missing the point. strcmp is used to compare character arrays (char*). Jayme is using the C++ string type, std::string. __________________ Me :: You :: Them

May 6th, 2006, 6:38 PM	#10
Cache Hobbyist Join Date: Sep 2005 Posts: 266 Rep Power: 4	I'd suggets using vectors, again. Then you can make use of iterators and algorithms. Assuming I'm following this thread right, I think this should do the trick: ( requires #include <algorithm> ) (Toggle Plain Text) std::vector<char>::const_iterator it = find( vec.begin(), vec.end(), "taskmgr.exe" ); if ( it != vec.end() ) { ::ShellExecute( NULL, "open", "notepad.exe", NULL, NULL, SW_SHOW ); } std::vector<char>::const_iterator it = find( vec.begin(), vec.end(), "taskmgr.exe" ); if ( it != vec.end() ) { ::ShellExecute( NULL, "open", "notepad.exe", NULL, NULL, SW_SHOW ); } Just the change the type in the vector if you're not using char*.

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May 6th, 2006, 10:20 AM	#2
grumpy Programming Guru Join Date: Jun 2005 Location: Adelaide, South Australia Posts: 1,260 Rep Power: 5	Your problem has nothing to do with string comparisons; the basic logic is wrong. The test of "if (vec.back())" is within the for loop. Which has the effect that, if the first entry in vec is not "notepad.exe", then notepad is launched. Thanks to the "break" statements your code will only ever look at the first entry in vec as well. If the entries in vec are obtained from the system, there may also be some path information (eg notepad.exe might be something like "C:\\WINNT\\notepad.exe").

May 6th, 2006, 10:23 AM	#3
Seif Hobbyist Programmer Join Date: Jan 2006 Location: UK Posts: 242 Rep Power: 3	try if (strcmp(ne, notepad.exe) == 0)

May 6th, 2006, 11:45 AM	#8
Seif Hobbyist Programmer Join Date: Jan 2006 Location: UK Posts: 242 Rep Power: 3	yeah my bad. have a massive hangover and didnt really read post properly or take a good look at the code. sorta just took a quick scim n see if there was any suggestions i could do to help. sorry. just read the final line... what a dumbass i am lol.

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Programming Forums > Application Development > C++

String comparison