blitz
/
blitz3d
mirror of https://github.com/blitz-research/blitz3d.git


			
				
					
						
						
							123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119
							<html>

<head>
<meta http-equiv="Content-Type"
content="text/html; charset=iso-8859-1">

<title>Language Reference - Program Flow</title>
<link rel="stylesheet" href="lang_ref.css" type="text/css">
</head>

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