Programmer Guide/Command Reference/WHILE: Difference between revisions
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Provided that the [[Programmer_Guide/Command_Reference_Intro/Conditional_Expressions|conditional expression]] <code>condition</code> holds true, the commands in the block enclosed by the <code>WHILE</code>, or <code>DO WHILE</code>, and the corresponding <code>END</code> statement are repeatedly executed until <code>condition</code> becomes false. | Provided that the [[Programmer_Guide/Command_Reference_Intro/Conditional_Expressions|conditional expression]] <code>condition</code> holds true, the commands in the block enclosed by the <code>WHILE</code>, or <code>DO WHILE</code>, and the corresponding <code>END</code> statement are repeatedly executed until <code>condition</code> becomes false. | ||
To put it more bluntly: The condition is always tested on the begin of the loop, that is, ''before'' executing the respective block of commands. With | To put it more bluntly: The condition is always tested on the begin of the loop, that is, ''before'' executing the respective block of commands. With {{STX}}, there is no explicit loop statement checking its condition at the end of the loop, but if this is what you are longing for, you will find relief by combining the [[Programmer_Guide/Command_Reference/FOREVER|FOREVER]] statement with an appropriate [[Programmer_Guide/Command_Reference/IF|IF]], and [[Programmer_Guide/Command_Reference/BREAK|BREAK]], statement. | ||
Note that it is perfectly legal to prematurely leave a loop with a <code>[[Programmer_Guide/Command_Reference/BREAK|GOTO]]</code> statement, though, generally, <code>GOTO</code> is considered harmful. | Note that it is perfectly legal to prematurely leave a loop with a <code>[[Programmer_Guide/Command_Reference/BREAK|GOTO]]</code> statement, though, generally, <code>GOTO</code> is considered harmful. | ||
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Revision as of 16:56, 5 April 2011
WHILE condition ... END
or
DO WHILE condition ... END
Provided that the conditional expression condition holds true, the commands in the block enclosed by the WHILE, or DO WHILE, and the corresponding END statement are repeatedly executed until condition becomes false.
To put it more bluntly: The condition is always tested on the begin of the loop, that is, before executing the respective block of commands. With STx, there is no explicit loop statement checking its condition at the end of the loop, but if this is what you are longing for, you will find relief by combining the FOREVER statement with an appropriate IF, and BREAK, statement.
Note that it is perfectly legal to prematurely leave a loop with a GOTO statement, though, generally, GOTO is considered harmful.
