Not grabbing data from struct array. - TIGCC Programming - Active Forums - TI-Chess Team HQ - Message Board - Message Board - Yuku

RSS
Email

0 Kudo

<< Previous Topic Next Topic >>

Not grabbing data from struct array.

Author	Comment
atarijedi	Not grabbing data from struct array.	Lead	[-]
Posts: 1 (2009-07-24 05:35:56) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Report Post	My program is for the Voyage 200 and I am using TiEmu and the OS image from Ti. Ok so I am trying to build a periodic table program. I have built a typedef struct that will hold element data, as well as position data for each cell. I only have 2 elements in it so far, Hydrogen and Helium, however when I try and draw the cell for Helium (index 1), nothing happens, Hydrogen (index 0) works fine though. I can't seem to figure out what is wrong. Here is a copy of my code http://pastebin.com/m7acbf7c7 Hopefully someone can help me.
Lionel Debroux		#1	[-]
Posts: 3027 (2009-07-24 07:37:31) Former Admin Reply Quote More My Recent Posts Message Me Connection Blocking Invite Report Post	Pastebin currently times out for me... could you upload it somewhere else ? (I can access various other sites, so it's not a problem on my side)
Lionel Debroux		#2	[-]
Posts: 3028 (2009-07-24 10:05:02) Former Admin Reply Quote More My Recent Posts Message Me Connection Blocking Invite Report Post	OK, Pastebin works for me now. The problem is the "e_cat" field of the ELEMENT_INFO struct. When computing the address of an element in the "elements" struct, it's interpreted by the compiler as having a zero size, though the contents of the string are actually stored in the table. In effect, elements[ 1 ].x == 0x4e6f, elements[ 1 ].y == 0x6e2d, elements [ 1 ].x_offset == 0x4d65 and elements [ 1 ].y_offset = 0x7461, i.e. the "Non-Metal" string interpreted as shorts. Instead of reserving the space for a "Non-Metal", "Noble Gases", etc. string, I advise you to make the "e_cat" field a short (or even a char, but that often results in less efficient code), which will be interpreted as an index to an array of strings that contains "Non-Metal", "Noble Gases", etc. That also goes for the "name" field. The "elec_shell" field could be of type 'unsigned char', that would save seven bytes per entry. If you are learning TI-68k programming through the making of a periodic table (or it's a homework, etc.), and you're having fun that way, by all means, that's fine with me However, note that multiple periodic table implementations for TI-68k calculators already exist. One of them is Samuel Stearley's Yet Another Periodic Table (YAPT). Last Edited By: Lionel Debroux 2009-07-24 10:09:07. Edited 1 times.
Kevin Kofler		#3	[-]
Posts: 7010 (2009-07-25 00:53:56) Admin Reply Quote More My Recent Posts Message Me Connection Blocking Invite Report Post	As Lionel basically explained, the problem is that you can't put a structure with a variable-length array into an array. Arrays can only contain fixed-size objects. A simpler solution is to just declare e_cat as const char e_cat* and let the compiler do the rest (constant merging of string literals, happens automatically). Yes, this will create 4-byte pointers and relocations instead of Lionel's 2-byte offsets. But it's much simpler for a beginner and also more readable. The only thing you need to change for that solution is char e_cat[] -> const char e_cat*.

<< Previous Topic Next Topic >>

Quick Reply