Thread: Segment fault on double whammy char pointer

Originally Posted by Emmanuel Delaha

The malloc() thing allocates room for an array of pointers, but the pointers of this array are not initialized. If you want to use them, you also must allocate some memory block and record its address in the array of pointers. You code must be completed.

Pointers are the tricky point of the C language. I suggest you work on it mre deeply before going further. It must be crystal clear in your mind.

Well I understand pointer basics, it's just the double whammies confuse me because it makes sense to me, just not to the compiler! Agh..

Originally Posted by Emmanuel Delaha

Would you please copy and paste your code (with comments if you want) so that we can get your original code for chack and test, and not some by-hand-and-full-of-typos copy...

The 'image' trick is just boring (and expensive in terms of disk space)

I have no typos for one (because I am perfect!). I thought you guys would like the anti-aliased color coating! & plus some lucky HTML folks might see that I'm using GIF, remember to use GIF on images with not that many colors! I could kind of understand on disk space, but now'a days we've got like 80 GB hd's. Plus it's good typing practice! And it's not a by-hand copy, it's completely electronic! I don't understand! I know a pointer wiz can do this, BE the compiler, I have faith in you Emmanuel, you are the compiler soldier! I'm here for you every step!

Hey long time no see Emmanuel

The first thing I notice is that you are casting the return value of malloc(). This is a big no no. Also where are you #include's? If you are getting errors about the void* then you are compiling it as c++ and should be using new and delete instead. Speaking of delete where are you calling free to deallocate the memory you malloc'd?

Here's a tip - copy/paste your code from your text editor into a set of [code][/code] tags.
sure it looks pretty, but it is absolutely USELESS to everyone else who want's to copy/paste your code for experiment or comment.

> char **Images = (char**)malloc(512);
1. Remove the cast (see the FAQ)
2. Add #include <stdlib.h>
3. Use a C compiler (not a C++ compiler which your code seems to need)
4. the size is totally bogus

Code:

char **Images = malloc( 512 * sizeof *Images );

> for(i=0; i<sizeof(Images); i++) {
What exactly are you hoping to achieve with this?
If it's an attempt to count the number of strings, then it fails miserably.

Man, is that all the code is supposed to do?
It's like a 5-second job in a shell script.

Code:

files="guard lobo"
for i in $files ; do
  wget http://www.fffin.com/ikonit/ff6/enemies/$i.gif
done

>Man, is that all the code is supposed to do?
>It's like a 5-second job in a shell script.

Heh. Well there is the whole learning experience too ya know.

> Well there is the whole learning experience too ya know.
Yes, futility is a lesson I suppose - Like cutting the lawn with scissors.

Another being recognising the best tool for the job.

Thank you guys for all of that help! (Especially the shell script!). So i was working on Version 3 of the C programmed get Images program, and BAM! Segment fault, so I laughed at the screen thinking it would be incredibly easy for me to solve this sucker--it wasn't! I know where the segment fault is, & it is highlighted in the source of the txt file that I uploaded. free() just doesn't like to be free! :(.

Could someone help me out with this segment fault?