Michael Fabain Dirks
119 lines
4.7 KiB
HTML
119 lines
4.7 KiB
HTML
<html>
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<head>
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<meta http-equiv="Content-Type"
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content="text/html; charset=iso-8859-1">
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<title>Language Reference - Program Flow</title>
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<link rel="stylesheet" href="lang_ref.css" type="text/css">
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</head>
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<body><br>
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<span class="Command"> Program Flow </span>
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<blockquote>
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<p>The following constructs are available for controlling program flow. </p>
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<p class="header">If ... Then </p>
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<blockquote> <i>If {expression} Then {statements1} Else {statements2} </i></blockquote>
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</blockquote>
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<p>
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<blockquote>
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<p>Evaluates the 'If' expression and, if true, executes the 'Then' statements.
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If false, the 'Else' statement are executed, the 'Else' part is optional -
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statements are executed until the end of the line.</p>
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<blockquote>
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<p><i>If {expression1}<br>
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{statements1} <br>
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Else If {expression2}<br>
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{statements2} <br>
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Else If {expression3}<br>
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{statements3}<br>
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Else <br>
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{statements4} <br>
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EndIf </i></p>
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</blockquote>
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<p> This form of the If statement allows for more than one line of statements.
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The 'Else If' and 'Else' parts are optional. The 'Else' part is executed only
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if none of the 'If' or 'Else If' expressions were true. </p>
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<p class="header">While ... Wend</p>
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</blockquote>
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<p>
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<p align="left">
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<blockquote>
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<blockquote>
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<p> <i>While {expression} <br>
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{statements} <br>
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Wend </i></p>
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</blockquote>
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<p> A While loop continues executing until {expression} evaluates to false.
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{expression} is evaluated at the start of each loop. </p>
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<p class="header">For ... Next</p>
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<blockquote>
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<p> <i>For {variable}={initalvalue} To {finalvalue} Step {step} <br>
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{statements} <br>
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Next </i></p>
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</blockquote>
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<p> A For/Next loop first assigns {initialvalue} to {variable} and then starts
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looping. The loop continues until {variable} reaches {finalvalue} and then
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terminates. Each loop, the value {step} is added to {variable}. If a step
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value is omitted, a default value of 1 is used. </p>
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<blockquote>
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<p><i> For {variable}=Each {typename} <br>
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{statements} <br>
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Next </i></p>
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</blockquote>
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<p>This form of the For/Next loop allows you to iterate over all objects of
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a custom type. </p>
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<p class="header">Repeat ... Until/Forever</p>
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</blockquote>
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<p align="left">
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<blockquote>
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<blockquote>
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<p><i> Repeat <br>
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{statements} <br>
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Until {expression} </i></p>
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</blockquote>
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<p> A Repeat loop continues executing until {expression} evaluates to true.
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{expression} is evaluated at the end of each loop. </p>
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<blockquote>
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<p><i>Repeat <br>
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{statements} <br>
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Forever</i> </p>
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</blockquote>
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<p>A Repeat/Forever loop simply executes {statements} until the program ends,
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or an 'Exit' command is executed. </p>
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<p class="header">Select ... Case</p>
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</blockquote>
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<p>
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<p align="left">
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<blockquote>
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<blockquote>
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<p> <i>Select {expression} <br>
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Case {expressions1}<br>
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{statements1} <br>
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Case {expressions2} <br>
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{statements2}<br>
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Default <br>
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{statements3} <br>
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End Select </i></p>
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</blockquote>
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<p> First the 'Select' expression is evaluated. It is then compared with each
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of the 'Case' expression lists. If it matches a 'Case', then the statements
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in the 'Case' are executed. </p>
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<p> If the 'Select' expression matches none of the 'Case' expressions, the statements
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in the optional 'Default' section are executed. </p>
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<p class="header">Breaking Out Of A Loop</p>
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<p> The 'Exit' command may be used to break out of any <b>For...Next</b>, <b>While...Wend</b>,
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<b>Repeat...Until</b> or <b>Repeat...Forever</b> loop. </p>
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<p class="header">Using Includes</p>
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<p>Blitz also supports the 'Include' command. Include allows source code from
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an external file to be compiled as if it were part of the main program. Include
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must be followed by a quote enclosed filename. For example... </p>
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</blockquote>
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<p>
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<p align="left">
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<blockquote> Include "anotherfile.bb"
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<p> Include allows you to break your program up into smaller, more manageable
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chunks. </p>
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</blockquote>
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</body>
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</html> |