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Full Discussion: Program received signal: “EXC_BAD_ACCESS”?
Top Forums Programming Program received signal: “EXC_BAD_ACCESS”? Post 302524558 by achenle on Monday 23rd of May 2011 08:45:20 PM
Old 05-23-2011
Quote:
Originally Posted by Corona688
Code:
char *string1;

This is a character pointer. On a 32-bit system, it takes 4 bytes, on a 64-bit system, 8 bytes. When I type in 'slartibartfast', where is it going to put it?

Inside the pointer? No, not enough room, and besides -- that's not how pointers work. The idea of a pointer is that it points to the memory you want to use, right?

So what memory have you got the pointer pointing to? Nothing? Uh-oh.

That leaves it at a random garbage value. Since pointers have no magic power of predicting what you want to do to them, it doesn't create memory for you to put things in and the pointer remains at what it started at -- some random garbage value. So scanf tries to store it in some undefined location in memory which naturally crashes

You should make the pointer actually point to something if you expect it to work. char string1[128]; or char *string1=malloc(128);
A string of characters such as "ABCD" is a character array. That we all know.

But an array evaluates to the address of it's first element, so when you see "ABCD" in an expression, it is effectively treated as a char *.

So the statement
Code:
char *string = "ABCD"

is perfectly valid. The pointer "string" is a char * value that is assigned the address of the first element of the "ABCD" array.

The OP's problem is he's trying to concatenate another string on the end of a static, constant array - his strcat() call is trying to write to the memory immediately following where his "tar czvf YourNewFile.tar.gz " string is stored.

And that appears to be read-only memory. Which is better than nuking whatever data is there.
 

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LEARN ABOUT ULTRIX

next

next(1mh)																 next(1mh)

Name
       next - show the next message

Syntax
       next [ +foldername ] [ -[no]header ] [ -help ] [ -showproc program ] [ -noshowproc ] [ options to ]

Description
       The  command  displays  the  next message in the current folder.  The next message is the one after the current message in the folder.  The
       message that is shown becomes the current message.

       If you name a folder using the +folder argument, displays the next message in the folder you specify.   That  folder  becomes  the  current
       folder.

Options
       -header
       -noheader Displays  a  one-line	header before the message.  The header consists of the name of the folder and the message number.  This is
		 the default behavior.	It can be suppressed with the -noheader option.

       -help	 Prints a list of the valid options to this command.

       -showproc program [ options ]
       -noshowproc
		 Specifies an alternative program to list messages.  The default is to use the program defined by the showproc: entry in the file.
		 As with you can give options to the program at the command line.  These are passed directly to by

       The defaults for this command are:

	      +folder defaults to the current folder
	      -header

Restrictions
       The  command  is  really  a  link  to  the program.  As a result, if you make a link to and that link is not called your link will act like
       instead.  To avoid this, add a profile-entry for the link to your and add the argument to the entry.

Profile Components
       Path:	   To determine the user's Mail directory
       showproc:   Program to show the message

Files
       The user profile.

See Also
       show(1mh), prev(1mh), mh_profile(5mh)

																	 next(1mh)
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