Oxygen Basic
Programming => Problems & Solutions => Topic started by: Aurel on May 03, 2013, 07:28:38 AM
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Hi Charles...
I just cach some time and continue to work on my little interpreter in oxygen
and again i see that SELECT stringVar not work.
I use latest oxygen dll.
this code not respond under SELECT statment:
print style
SELECT style
'MinMaxSize -> overlapped window
Case "#MMS"
print "STYLE is MINMAX"
wStyle = WS_MINMAXSIZE
Case "#SYS"
wStyle = WS_SYSMENU
END SELECT
And when i use IF/ELSEIF/ENDIF then string variable is compared.
IF style = "#MMS"
wStyle = WS_MINMAXSIZE
END IF
So like you see something is wrong with SELECT when we select string variable name,right?
Do you can fix this?
I know that with IF works but is very strange that not work with ordinary SELECT..
Aurel
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Hi Aurel,
Select does not work with whole strings, only ascii characters, like this:
select asc s
case "A" to "Z" : ...
case "-" : ...
case 1 to 32 : ...
end select
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And why not work with whole string ?
In most of other basic-s this thing work without any problems.
Do you will add this possibility in some of the next versions ?
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I don't really want to change this behaviour. The case block is for making 'atomic' comparisons very fast. It can do so faster than if..elseif..endif, which is more suited to complex comparisons, like strings.
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Yes, I like Select Case how it is.
A good consideration, Charles
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Ok..
So if i want compare strings i must use if/elseif/endif....
I use this method and it looks that work fast.
Hmmm ..maybe will be good to fill commands array with number which represent
command instead with strings and then use select...
like pseudo code:
LET a = 5
with
10 , a ,= ,5
I will see... ;)
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Charles ..
is there maybe another method which can fast compare strings ?
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Yes, I like Select Case how it is.
I'm thankful Peter prefers IF {then} ELSE over CASE as converting his games would have made the port to ScriptBasic more time consuming and I probably wouldn't have bothered.
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For short lists of strings, instr performs well.
function Lookup(string list,k) as sys
=====================================
sys p,v
lk=len k
do
p=instr(p+1,list,k)
if p=0 then exit do
if p
if asc(list,p-1)<33 and asc(list,p+lk)=44
v=asc(list,p+lk+1)-48
exit do
end if
end if
end do
return v
end function
list="
left,1
right,2
top,3
bottom,4
above,5
below,6
"
k="top"
print k " " Lookup(list,k)
Charles
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Thanks Charles ...
This is a nice function...
I have one small question about string literal with quotes..
FUNCTION GetStrLiteral(byval quotedStr as string) as String
String strOut
print quotedStr + LEN(quotedStr)
strOut = Mid(quotedStr,2,LEN(quotedStr)-2)
print "StrOUT:" + strOut
Return strOut
END FUNCTION
As you can see ,if I need return quoted string without quotes i must use LEN(qs)-2
instead LEN(qs)-1
even if LEN return proper string len ???
Is this normal or something is wrong ?
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Yes -2 is correct
function NoQuotes(string s) as string
if asc(s)=34
return mid s,2,len(s)-2
else
return s
end if
end function
print NoQuotes `"Hello"`
Charles
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I just don't get it. Can you help me find my hands?
(http://files.allbasic.info/AllBasic/ears.jpg)
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Charles..
Is this because null terminated string on the end ?
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No. You -2 for the number of quotes (2) that surround the enclosed string.
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No ..
Is not...because when i use -1 i get as output string
string"
do you get it now expert
If you don't understand test this expert
'literal
FUNCTION GetStrLiteral(byval quotedStr as string) as String
String strOut
print quotedStr + LEN(quotedStr)
strOut = Mid(quotedStr,2,LEN(quotedStr)-1)
print "StrOUT:" + strOut
Return strOut
END FUNCTION
string s,sout
s = chr(34) + "qstring" + chr(34)
sout = GetStrLiteral(s)
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Yep, that is what I would expect to see when you are only removing the quote at the start of the string. (length of string - 1) I had to stay at a Holiday Inn Express for a week to figure that one out.
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No
it looks that you don't see that start position is 2
expert... ;D
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Why would you start reading the string at the beginning when you know your passing the function a quoted string to strip?
aka Expert
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Why would you start reading the string at the beginning when you know your passing the function a quoted string to strip?
yes,why?
you still don't get it,because this quoted string is argument or token and is used from token array
as string literal.
do you get it now?
Just to confirm that is null terminated i made test in EBasic ..
look shots...
X
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That is why i am confused ...on first look i think that string is trimmed
and that is why i think that is proper to use -1 with Mid() function.
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Lets look at Charles example and comment it line by line.
function NoQuotes(string s) as string ' s is going to be a string of some unknown length surrounded by quote characters
if asc(s)=34 ' check to see if a quoted string is being passed. (asc() only looks at the first character)
return mid s,2,len(s)-2 ' return the second character on to the length of the string - 2 (which truncates the trailing quote)
else
return s ' you didn't pass a quoted string so here is what you sent
end if
end function
print NoQuotes `"Hello"` ' the single quote allows passing the double quotes as part of the argument
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You may comment what you whish and you again not look into screenshots,right?
my argument is arg["qString"]
and not arg["qString" ]
do you get it now?
so -1
give this :
[qString"]
and -2
give this:
[qString]
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Things seem to be bouncing off all the walls.
Are you testing O2's unique ability to use an array reference as function call?
I'm quickly losing your point.
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Oxygen strings have an indexbase of 1 and the len function ignores null terminators.
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Oxygen strings have an indexbase of 1 and the len function ignores null terminators.
Hi Charles..
Good to know, and when is used - like in my case in function .
And is important to me ;)
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Charles...
Just one small question if is no problem.
For example if i decide to replace string array with integer array as
command code...like
Instead of PRINT i use int number 1.
( i see something similar in rexx-imc code /)
So then i can use SELECT , right?
like
SELECT keycode
CASE 1
.....
CASE 2
....
What you mean how much faster i can get execution ?
thanks..
Aurel ;)
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You can do.
include "sw.inc"
window 320,240,1
while key(27)=0
cls RGB 255,255,255
a = GetKey
select a
case vk_0
Text 0,0,"pressed " + chr(a),0
case vk_1
Text 0,0,"pressed " + chr(a),0
case vk_2
Text 0,0,"pressed " + chr(a),0
case vk_3
Text 0,0,"pressed " + chr(a),0
case vk_4
Text 0,0,"pressed " + chr(a),0
end select
Sync
wend
Quit