Thread: Using a string to point to a string??

Working on a program in C, where I am trying to replace some code to make it more generic. The code is

Code:

     x2 = Arial30_a_Size[0];
     y2 = Arial30_a_Size[1];
     c = &Arial30_a;

Arial30_a_Size is [code]const int Arial30_a_Size[]={23,40};[\code]
and Arial30_a is a much larger array that starts like this

Code:

const unsigned short Arial30_a[] ={249,0x00,8,0xFF, 14,0x00,12,0xFF,. . . . .

Arial30 is a font, for which each character of the font has the two arrays as above.

To make the code easier to change between different fonts, I have tried the following:

Code:

char Font1[] ={"Arial30"};  //name of one font
char Font2[] = {"Arial20"}; //name of another font
char local1[30]={0x00}, local2[30]={0x00},local3[20]={0x00};
//create 3 strings to build the need pointers
//now cat together each string
     strcat(local1,Font1);
     strcat(&local1,"_a_Size[0]");
     strcat(local2,Font1);
     strcat(&local2,"_a_Size[1]");
     strcat(&local3,"&");
     strcat(local3,Font1);
     strcat(&local3,"_a");
 //local1 now has "
Arial30_a_Size[0]"
//local2 now has "
Arial30_a_Size[1]"
//local3 now has "
&Arial30_a"
//NOW COMES THE PROBLEM!  I need to assign the value held by
//
&Arial30_a to c, 
Arial30_a_Size[0] to x2, and 
Arial30_a_Size[1] to //y2 and I cannot figure out how.  I have tried * and &, but only get //the value of the first letter in the string
     x2 = local1;
     y2 = local1;
     c = local3;

Any help would be appreciated,
Kind regards,
David

int *c;
x2 and y2 are just int's
Thanks for your response
David

Originally Posted by laserlight

I suggest that you simplify this so that you only show what you're trying to do for a single thing, not for three things at once. So, let's take this as an example:

Code:

char Font1[] = "Arial30";
char local3[20] = "";
strcat(local3, "&");
strcat(local3, Font1);
strcat(local3, "_a");

Notice that:

• I omitted the braces around "Arial30".
• I wrote "" since you were trying to initialise the arrays to hold empty strings.
• I did not take the address of local3 when passing it as an argument to strcat: local3, being an array, will be converted to a pointer to its first element, to you should not take its address unless you really want a pointer to the entire array of char rather than a pointer to char.

Next, from what I understand, you "need to assign the value held by &Arial30_a to c". What is c? You didn't show the declaration of c. The thing is, local3 stores the string "&Arial30_a". This string doesn't hold a value (other than itself, I guess). I suspect that you might be thinking of the "variable variables" feature that some programming languages C, but that is not a C language feature. If you elaborated on what is c and what is &Arial30_a, maybe we could suggest an appropriate alternative (a balanced binary tree map? a hash table?)

Arial_a is an array that I use to display the character a in an Arial 30 font. Contents are

Code:

const int Arial30_a_Size[]={23,40};    //size of the character in pixels (23 wide, 40 high)
const unsigned short Arial30_a[] ={    //the first 249 bits of the character are the background color, then 8 bits are white, the next 114 bits are the background color . . . . .
249,0x00,8,0xFF, 14,0x00,12,0xFF, 11,0x00,14,0xFF, 9,0x00,5,0xFF, 5,0x00,6,0xFF, 7,0x00,
5,0xFF, 8,0x00,4,0xFF, 7,0x00,4,0xFF, 9,0x00,4,0xFF, 20,0x00,4,0xFF, 18,0x00,6,0xFF, 
13,0x00,11,0xFF, 10,0x00,14,0xFF, 9,0x00,10,0xFF, 1,0x00,4,0xFF, 8,0x00,6,0xFF, 6,0x00,
4,0xFF, 7,0x00,5,0xFF, 8,0x00,4,0xFF, 7,0x00,4,0xFF, 9,0x00,4,0xFF, 7,0x00,4,0xFF, 
9,0x00,4,0xFF, 7,0x00,4,0xFF, 8,0x00,5,0xFF, 7,0x00,4,0xFF, 7,0x00,6,0xFF, 7,0x00,
5,0xFF, 5,0x00,7,0xFF, 8,0x00,16,0xFF, 9,0x00,9,0xFF, 2,0x00,4,0xFF, 11,0x00,5,0xFF, 
5,0x00,4,0xFF, 217,0x00, 254};                                                                                       //254 is the terminator of the character

Thanks for the suggestion of how to make this work - especially the EDIT - that makes more sense. I appreciate your time in helping me.
Kind regards,
David