lepricaun

can someone please tell me what i've done wrong? i've read several tut's on pointers now, but still can't get this to work

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Ooble

Well, what happens?

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Infinite Recursion

I hate pointers, I avoid using pointers like so... (btw, if it wasn't obvious this is C++)

#include <windows.h>
#include <iostream>
#include <string>

int main(void)
{
string run;
cout << "\nCommand:>";
cin >> run;
WinExec(run.c_str(), SW_NORMAL);
return 0;
}

---

Typing 'control.exe' as your command, will bring up the Control Panel.

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Kylixen

scanf("%s", &variable_that_is_not_a_pointer);

I mean, really. Do you want to be responsible for telling someone to use CIN and COUT instead of scanf and printf?? Dont' be scared of pointers, embrace them. They are hella powerful.

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Infinite Recursion

Ok... so here is the C code to run a command less than 50 characters.


Yes, I do.

Pointers have their uses... when they are not necessary, I don't use them.

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lepricaun

what a response

thanks for the help, now i have only one question left:

how must i alter this to take parameters? like "c:\program files\internet explorer\iexplore.exe http ://www. programmingforums.org"

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Infinite Recursion

Notice the line:
int main(int argc, char *argv[])

This is how you get command line parameters into your program. 'argc' is the parameter count, 'argv' is the array of parameters.

argv[] starts at index 0.

So when you compile this code into an exe... you run like so:

C:\myRun control.exe

Control panel will open up for you.

Note:
argv[0] is the program's name (in this case the value us 'myRun')
argv[1] is the first exe you want to run...

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Ooble

Erm... I think he means in the WinExec function. This is what you need to do. I'm assuming it doesn't already work as it is, as I can't be bothered to test it (remember, if there are spaces in the path, you need to use double-quotes).

If there are quote marks encompassing the path, separate the path from the arguments by using two different variables ("path" and "args" are probably your best choices). If not, first check the entire string isn't a file by opening it for reading and checking the return value (look at fopen() ). If it is, execute it. Otherwise, assume the path is the entire string up to the first space. Separate the path and the arguments and add quotes round the path.

Finally, do this:
If there ever was a problem in the first place, that should fix it

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Infinite Recursion

The code I provided earlier works fine... to accomplish parameters. Compile it into an exe and run it as follows (be sure to include the "):

Assuming you named it 'myRun':

myRun "c:\program files\internet explorer\iexplore.exe http://www.programmingforums.org"


---


Assuming you want to run multiple exes:

You could modify the code to do this:

WinExec(argv[1],SW_SHOW);
WinExec(argv[2],SW_SHOW);
WinExec(argv[3],SW_SHOW);

To allow for this:

myRun prog1 prog2 prog3


Works fine... and fairly flexible.

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kurifu

In this example you have successfuly set aside memory to hold a pointer address

char* run;

however when that is initialized it will point to 0xcdcdcdcd, NULL, or some random memory address depending on the compiler and debugging options built into the project. The step you are missing is actuuallt setting aside memory to point to.

run = new char;

This will set aside 1 char of memory and assign the memory address the pointer need into run, so that it may be used.

If you only intend on using 1 byte, or you intend on using a fixed array of bytes, try using something more like this

char run;
scanf( ..., &run );

The ampersand takes the memory address of run instead of the value of run.

Watch out for buffer overflows though, if you read values directly into an array that is not large enough to hold the input you will likely corrupt your heap/stack.

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