Hi,
So, I have this string:
Code:
.db "ABCDEFG"
How do I display 1 character of this string, like the "C"?
Thanks!
Here's a version of the canonical PutS, which should provide you with enough of a nudge in the right direction:
Code: PutS:
; Read character from buffer
ld a,(hl)
inc hl
; Stop if zero (end-of-string)
or a
ret z
; Display the character in a
bcall(_PutC)
; Continue with next character
jr PutS
If you're familiar with PutS, you'll know that you point HL at the string you want to display.
Thus, in general, to display a character, you want to get it in A and call PutC. It might be as easy as loading the character value into A, or in most cases (including this one, it looks like) you'll read a byte from memory and use that.
aeTIos, _PutC is exactly what you want, or _vputmap if you want the small (graphscreen) font.
Can someone give a code example?
I have a the value 3 in a and i want the A'th character of this string:
Code:
.db "ABCDEFGHI"
I just started learning ASM, so I didnt get really what The Tari meant.
Something like this:
Code: ; A = 3 coming in
; Adjust index (first character is indexed at 0)
dec a
; DE = A
ld e,a
ld d,0
; Point HL to string
ld hl,str
; HL -> str + A, the character we want
add hl,de
; Read character..
ld a,(hl)
; ..display
bcall(_PutC)
str:
.db "ABCDEFGHI"
I agree completely! AeTIos, notice especially the change from index-from-1 to index-from-0. If you can, it's ideal to design your systems to index from 0 instead of 1.
Yep, it's always easier in just about every language except TI-BASIC to start counting from zero.
That was very clear! Thanks!
Deep Thought wrote:
Yep, it's always easier in just about every language except TI-BASIC to start counting from zero.
And Matlab! That's the other important exception that makes me a sad panda.
KermMartian wrote:
Deep Thought wrote:
Yep, it's always easier in just about every language except TI-BASIC to start counting from zero.
And Matlab! That's the other important exception that makes me a sad panda.
I didn't know kermM was a panda. But yeah, dealing with trying to figure out if it starts with 0 or 1 was difficult at first, but I love starting with 0 now.
I learned QBASIC first, which didn't really have arrays, then TI-BASIC, so 1-offset was pounded into my head, but the same year I learned x86 ASM, then Perl, then PHP, then C, so I was swiftly switched to automatic 0-indexing. The only anomaly after that was Matlab.
KermMartian wrote:
I learned QBASIC first, which didn't really have arrays, then TI-BASIC, so 1-offset was pounded into my head, but the same year I learned x86 ASM, then Perl, then PHP, then C, so I was swiftly switched to automatic 0-indexing. The only anomaly after that was Matlab.
QBASIC has arrays. I'm pretty sure you could even reference index 0 in them. (When you DIM an array it would actually be 1 element larger than you asked for, so you could use it with either 0- or 1-indexing)
Christop, pardon, my post was extremely imprecise. I should have said "I learned QBASIC first, but didn't really use arrays." I think there was a disconnect between my brain and my fingers when I typed that sentence. That's cool to know about the indexing (although the trick would then be consistency!).
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