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Pass char * list as function parameter
James Stanley
Member #7,275
May 2006
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Posted on 12/03/2006 5:48 AM   View Profile

I am writing a text spinner control for my GUI, and when creating the control, I have a function called new_selection. One of the parameters is a list of the values that can be selected. At the moment it is char *values[], but it causes a segfault when a value is accessed. The create code is:

1//gui.h:
2typedef struct SELECTION {
3 int x;
4 int y;
5 int w;
6 int h;
7 int value;
8 char *values[];
9 int numvalues;
10 int grey;
11 int cont;
12 BUTTON *leftarrow;
13 BUTTON *rightarrow;
14} SELECTION;
15 
16//gui.c:
17SELECTION *new_selection(int x, int y, int value, char *values[], int length, int numvalues) {
18 SELECTION *tempry = (SELECTION *)malloc(sizeof(SELECTION));
19 int n, i;
20 
21 tempry->x = x;
22 tempry->y = y;
23 tempry->leftarrow = new_button(x, y, -1, -1, "<");
24 n = (length * text_length(font, "M")) + 4;
25 tempry->rightarrow = new_button((x + tempry->leftarrow->w + n), y, -1, -1, ">");
26 tempry->w = (tempry->rightarrow->x + tempry->rightarrow->w) - x;
27 tempry->h = tempry->leftarrow->h;
28 tempry->value = value;
29 for(i = 0; i < numvalues; i++) {
30 tempry->values<i> = values<i>;
31 }
32 tempry->numvalues = numvalues;
33 tempry->grey = 0;
34 tempry->cont = 0;
35
36 return tempry;
37}

NOTE: This is actually compiled as C++ and the file name is gui.cpp, but I do not like to use C++ and I am only using so that I will be able to use OpenLayer. Also, there is nothing wrong with my new_button() function. It works fine on it's own. The offending peice of code is:

selection->values[selection->value]

It is passed as the value parameter to textout_centre_ex. Can anybody suggest a way of fixing this?
Thanks.

EDIT:
Never mind, changing it to char **values worked. I wonder why I didn't think of that before...

Three Harris
Member #6,226
September 2005
Posted on 12/03/2006 8:48 AM   View Profile

I am not 100% sure but it looks like you might have a fence-post error. Doesn't your compiler give you some kind of warning about char *values[] being assumed to be of size 1?

[on a second note]
Just because you allocate space for SELECTION doesn't mean that values[] can be of any size.

James Stanley
Member #7,275
May 2006
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Posted on 12/03/2006 12:26 PM   View Profile

No, there were no warnings at all. It doesn't matter anymore anyway.

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