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Hello,
Of course this release is dedicated to those wondering if I
have
any time left to code after a child is born :-)
Seriously, here is some more information on while,
for and if-else
statements syntax:
The while statement lets you repeat a statement until a specified
expression becomes false.
Syntax
while ( expression ) statement
The expression must have arithmetic (numeric/boolean) type.
Execution proceeds as follows:
The expression is evaluated.
If expression is initially false, the body of the while
statement is never executed, and control passes from the while
statement to the next statement in the program.
If expression is true (nonzero), the body of the statement
is executed and the process is repeated beginning at step 1.
This is an example of the while statement: i = 10;while( i < 20 ){ Plot( MA( Close, i ), "MA" + WriteVal( i, 0 ), colorBlack + i ); i = i + 1;}
The example plots 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 -
bar moving averages.
-----------------
The for statement lets you repeat a statement or compound statement a
specified number of times. The body of a for statement is executed zero
or more times until an optional condition becomes false.
Syntax
for ( init-expression ; cond-expression
; loop-expression ) statement
Execution of a for statement proceeds as follows:
The init-expression, is evaluated. This specifies the
initialization for the loop. There is no restriction on the type of
init-expression.
The cond-expression, is evaluated. This expression must have
arithmetic type. It is evaluated before each iteration. Three results are
possible:
If cond-expression is true (nonzero), statement is
executed; then loop-expression, if any, is evaluated. The
loop-expression is evaluated after each iteration. There is no
restriction on its type. Side effects will execute in order. The process
then begins again with the evaluation of cond-expression.
If cond-expression is false (0), execution of the for
statement terminates and control passes to the next statement in the
program.
This example illustrates the for statement: myema[ 0 ] = Close[ 0 ];for( i = 1; i < BarCount; i++ ){ myema[ i ] = 0.1 * Close[ i ] + 0.9 * myema[ i - 1 ];}This example iterates all bars of close array to calculate exponential moving average
---------
if, else Statements
if( expression )statement1 [else
statement2]
The if keyword executes statement1 if expression is true
(nonzero); if else is present and expression is false (zero), it
executes statement2. After executing statement1 or
statement2, control passes to the next statement.
Example 1if ( i > 0 )
y = x / i;
else
{
x = i;
y = abs( x );
}
In this example, the statement y = x/i; is executed if
i is greater than 0. If i is less than or equal to 0,
i is assigned to x and <FONT
face="Courier New">abs( x ) is assigned to y.
Note that the statement forming the if clause ends with a semicolon.
When nesting if statements and else clauses, use braces to
group the statements and clauses into compound statements that clarify your
intent. If no braces are present, the compiler resolves ambiguities by
associating each else with the closest if that lacks an
else.
Example 2if ( i > 0 ) /* Without braces */
if ( j > i )
x = j;
else
x = i;
The else clause is associated with the inner if statement in
this example. If i is less than or equal to 0, no value is assigned
to x.
Example 3if ( i > 0 )
{ /* With braces */
if ( j > i )
x = j;
}
else
x = i;
The braces surrounding the inner if statement in this example make the
else clause part of the outer if statement. If i is
less than or equal to 0, i is assigned to x. Best
regards,Tomasz Janeczkoamibroker.com
<BLOCKQUOTE
>
----- Original Message -----
<DIV
>From:
Tomasz Janeczko
To: <A title=amibroker@xxxxxxxxxxxxxxx
href="">amibroker@xxxxxxxxxxxxxxx
Sent: Sunday, April 13, 2003 11:07
AM
Subject: [amibroker] AmiBroker 4.31.0
BETA released
Hello,
A new beta version (4.31.0) of AmiBroker has just been
released.
It is available for registered users only from the members
area at:
<A
href="">http://www.amibroker.com/members/bin/ab4310beta.exe
If you forgot your user name / password to the members
area
you can use automatic reminder service at: <A
href="">http://www.amibroker.com/login.html
This release brings huge improvement to AFL:
for and while loops and
if-else flow control statements.
Native AFL loops run 2..3 times faster than JScript
(according to my
preliminary tests on arrays with 1000-5000
bars)
For more details and example code please read the following
"READ ME" text.
NOTE: from now on all beta releases will be available to
registered
users only (in member area).
Best regards,Tomasz
Janeczkoamibroker.com
AmiBroker 4.31.0 Beta Read Me
April 13, 2003 10:38
THIS IS AN EARLY BETA VERSION OF THE SOFTWARE. EXPECT BUGS
!!!
AGAIN: THIS IS AN EARLY BETA VERSION OF THE SOFTWARE. EXPECT BUGS
!!!
Backup your data files and entire AmiBroker folder
first!
INSTALLATION INSTRUCTIONS
IMPORTANT: This archive is update-only. You have to install full
version 4.30 first.
Just run the installer and follow the instructions.
Then run AmiBroker. You should see "AmiBroker 4.31.0 beta" written in the
About box.
CHANGES FOR VERSION
4.31.0 (as compared to 4.30.0)
Workspace window uses "icon font" set in the Windows settings instead of
hard coded Tahoma 8
for better readability and ClearType(tm) compatibility on WinXP, all
dialog windows use now 'MS Shell Dlg' face name that maps to standard MS
Sans Serif on Win 9x/Me/NT and Tahoma on Win 2K and XP.
rewritten AFL parser, now formula is parsed and coverted to syntax tree
and then interpreted. This would allow further improvements including
compilation. This allowed also to add loops/if-else statements.
implemented IF/ELSE statement, WHILE and FOR loops:The same basic
'for' loop in AFL is 2..3 times faster than in JScriptSyntax follows
C++/JScript style:
while( conditional_expression ) statement;
for( initializer_part; conditional_expression; iterator_part )
statement;
if( conditional_expression ) statement;
if( conditional_expression )
statement;elsestatement;
implemented compound statements: these are blocks of statements
enclosedin opening and closing curly brace
{statement1;statement2;...statementN;}
compound statement can appear anywhere when simple statement can.
For example:
i = 10;while( i < 20 ){Plot( MA( Close, i ), "MA" +
WriteVal( i, 0 ), colorBlack + i );i = i + 1;}
implemented C-style postfix and prefix increment/decrement operators
i = 10;WriteIf( i++ );WriteIf( ++i );WriteIf( i
);
implemented array element access (subscript) operator []:
WriteVal( Close[ 0 ] ); // prints the first bar of close
array
/* a sample low-level implementation of exponential moving average
in AFL */
myema[ 0 ] = Close[ 0 ];
for( i = 1; i < BarCount; i++ ){myema[ i ] = 0.1 *
Close[ i ] + 0.9 * myema[ i - 1 ];}
added built-in constant 'BarCount' that returns number of bars available
in arrays (the number of elements of array)When QuickAFL is turned on it
may be less than true number of bars because QuickAFL feature attempts to
use only visible bars (and few before). You can control how many bars the
formula requires using SetBarsRequired() function
implemented infinite-loop protection. Nice if you forgot to increment
counter variable in 'for' loop :-)
tab key now works without need to press ALT/CTRL in AFL editors
added C-like synonyms for logical ADD/OR/NOT: &&, ||, !
/* a sample low-level implementation of Profit-target stop in
AFL: */
Buy = Cross( MACD(), Signal() );
priceatbuy=0;
for( i = 0; i < BarCount; i++
){ if( priceatbuy == 0 && Buy[
i ] ) priceatbuy = BuyPrice[ i
];
if( priceatbuy > 0 &&
SellPrice[ i ] > 1.1 * priceatbuy
) { Sell[
i ] = 1; SellPrice[ i ] = 1.1 *
priceatbuy; priceatbuy =
0; } else Sell[
i ] = 0;}
/* sample EMA rainbow */
Plot( Close, "Price", colorBlack, styleCandle );for( Range =
15; Range < 100; Range++ ) Plot( EMA( Close, Range
), "MA"+WriteVal(Range,0), colorRose + Range % 8, styleNoLabel );
HOW TO REPORT BUGS
If you experience any problem with this beta version please send detailed
description of the problem (especially the steps needed to reproduce it) to <A
href="">bugs@xxxxxxxxxxxxx Send
BUG REPORTS to bugs@xxxxxxxxxxxxxSend SUGGESTIONS to
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Send BUG REPORTS to bugs@xxxxxxxxxxxxx
Send SUGGESTIONS to suggest@xxxxxxxxxxxxx
-----------------------------------------
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