Thread: Contiguous Array version of Linked List

Assuming there is already something in the array. It should cycle through the for loop, copy the element into the adjacent spot, then write over the spot directly infront of position..

Need I say it again? Get rid of that *** +1!!!

Here's what's happening. You get an array like this:

Code:

position = 3
element_count = 4
elementArray = {1, 2, 3, 4, x, x, ...}

You shift 4 over, since it is the only element >position.

Code:

elementArray = {1, 2, 3, 4, 4, x, ...}

And then you assign to elementArray[position+1].

Code:

elementArray = {1, 2, 3, 4, 123, x, ...

While that works, I'm sure you intended to have

Code:

elementArray = {1, 2, 3, 123, 4, x, ...

which is what you get without that +1.

Just so you know, if you access uninitialized memory or whatever, you're not guaranteed to get a segmentation fault. (Though on Linux your chances of getting a seg fault are very high.) So just because it runs doesn't mean that it doesn't access uninitialized memory.

Segmentation faults are good, by the way. At least they tell you that something's wrong. There's nothing worse than discovering a bug in code that you thought was solid, tested code . . . and then you think "Why on earth was that code working at all???" and then you have to modify tons of code because all of your code was assigning 1 to position instead of 0 . . .

[See the edits to my previous post, they're extensive.]

Oh, by the way, don't use gets(). Among other things . . . Food for thought:

Code:

$ gcc -W -Wall -ansi -pedantic -g -c *.c
Vector.c: In function ‘vectorCreate’:
Vector.c:40: warning: control reaches end of non-void function
Vector.c: At top level:
Vector.c:33: warning: unused parameter ‘size’
Vector.c: In function ‘vectorDelete’:
Vector.c:68: warning: control reaches end of non-void function
Vector.c: At top level:
Vector.c:61: warning: unused parameter ‘this’
Vector.c: In function ‘vectorSum’:
Vector.c:95: warning: control reaches end of non-void function
Vector.c: At top level:
Vector.c:88: warning: unused parameter ‘result’
Vector.c:88: warning: unused parameter ‘src1’
Vector.c:88: warning: unused parameter ‘src2’
Vector.c: In function ‘vectorDiff’:
Vector.c:122: warning: control reaches end of non-void function
Vector.c: At top level:
Vector.c:115: warning: unused parameter ‘result’
Vector.c:115: warning: unused parameter ‘src1’
Vector.c:115: warning: unused parameter ‘src2’
Vector.c: In function ‘vectorScalarProd’:
Vector.c:148: warning: control reaches end of non-void function
Vector.c: At top level:
Vector.c:141: warning: unused parameter ‘result’
Vector.c:141: warning: unused parameter ‘src’
Vector.c:141: warning: unused parameter ‘scalar’
Vector.c: In function ‘vectorInnerProd’:
Vector.c:175: warning: control reaches end of non-void function
Vector.c: At top level:
Vector.c:168: warning: unused parameter ‘src1’
Vector.c:168: warning: unused parameter ‘src2’
Vector.c:168: warning: unused parameter ‘ip’
$

I see what you mean, but then position is pointing to the newly added element. It is supposed to be pointing to the same one.

For instance:

Code:

elementArray = {1, 2, 3, 4, x, x, ...}
elementArray = {1, 2, 3, 4, 4, x, ...}
elementArray = {1, 2, 3, 3, 4, x, ...}
elementArray = {1, 2, 3, 9, 4, x, ...}

There is also an error somewhere with this->position--; being called. If I call listPosition() it seems to subtract one from position (as in it will iterate backwards, then loop back around to the tail). I don't see that happening anywhere in List.c

I think the error is in listHead and/or listTail... They're being called by something... Damn this abstracted nonsense.

As for gets() my compiler warns me every time, but I'm not even sure where it's being used. I know fgets() is a lot more stable, but how do you use it without a file?

Perhaps the wonders of Doxygen will help you with this. It's really quite neat the way you can click on a function and it brings you there. But in this case you can go to the entry for listHead and see which functions it is referenced by:

Code:

List* listHead  	(  	List *   	 this  	 )   	

Definition at line 148 of file List.c.

Referenced by main(), vectorRead(), and vectorWrite().

Ditto for listTail.

Code:

List* listTail  	(  	List *   	 this  	 )   	

Definition at line 180 of file List.c.

Referenced by main().

Anyway, you can have a look at it if you like. It's a .tar.gz masquerading as a .txt, as usual -- 66.3 KB.

As for gets() my compiler warns me every time, but I'm not even sure where it's being used. I know fgets() is a lot more stable, but how do you use it without a file?

Use stdin for the file, of course. Just remember to strip the newline that it returns if you want to use it directly where gets() was being used before. See the FAQ for details.