system("pause") crashing my app

Hello all,

I recently was doing an assignment for my c class and I ran into a small problem.

I haven't started much on the rest of the program, and I am currently decoding the command line arguments

It seems whenever I use system("pause"); at the end of my program (before return 0;) it crash and I have no idea why.

It has to do with the concat's I'm using. Commenting out those stops the crashes.

Here is my code (I commented most of it out):

Code:

#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>	// I like my booleans
#include <string.h>
#include "lc3.h"

int main(int argc, char* argv[])
{

	int CLA = 2; 	// override found command line arguments
			// (setting this as 8 or 0 also crashes the program)

	if((CLA & 2) == 2) //if -b
	{
		if(strstr(argv[argc-1],".bin")==null)  // if .bin is not in the filename
		{
			strcat(argv[argc-1],".bin");  // concat .bin to the filename
		}
	}
	
	if((CLA & 8) == 8) //if -m
	{
		if(strstr(argv[argc-1],".mco")==null)  // if .mco is not in the filename
		{
			strcat(argv[argc-1],".mco");  // concat .mco to the filename
		}
	}
	
	if((CLA & 10) == 0) //if not -b or -m
	{
		if(strstr(argv[argc-1],".hex")==null)  // if .hex is not in the filename
		{
			strcat(argv[argc-1],".hex");  // concat .hex to the filename
		}
	}
	
	printf("\n\n&#37;s",argv[argc-1]);
	
	printf("\n\n");
	system("pause");  // if I remove this, my program ends succesfully
	return 0;
}

any idea why its not working?

Thanks,
Kairos

I'm pretty sure it's crashing before then - perhaps because you are writing over the end of the argv[] strings - since there is absolutely no guarantee that argv[] has any space beyond the actual content, you can't use strcat() on argv[].

--
Mats

ok. That was my problem. When I created a new string with enough space it didn't crash.

I still find it odd that the only time it crashed was when I used system("pause"); Well C is funny like that I guess...

Thanks for the help,
Kairos

Originally Posted by KairosDrasis

I still find it odd that the only time it crashed was when I used system("pause"); Well C is funny like that I guess...

Yes, it's funny that way - that's probably the first time you acutally used the memory that you had overwritten, hence it crashes then, not before - without slowing things down dramatically, there is really no way to catch this sort of badness.

--
Mats

You should get rid of the habbit to use system("pause") for pausing the program's input. You could use _getch (or it's macro without an underline) or if you program in C++ cin.get().

Originally Posted by hauzer

You should get rid of the habbit to use system("pause") for pausing the program's input. You could use _getch (or it's macro without an underline) or if you program in C++ cin.get().

yeah... but its so easy to put system("pause") XD. I'm programming in C and I only use it when I'm using Dev-C++ because the window disappears in a flash. I think I heard that its not compatible with anything but windows, but just doing homework for class it don't really matter. We normally don't need to put a pause but I do it because I refuse to use vim.

Thanks again to all.

How do I mark this topic as answered/completed?

You don't really need to do that...
If your question has been answered, you just need to avoid replying in it.