====== if ======


===== Description =====

Test the value of a condition, and if true, execute a statement block. 

===== Statement prototype =====

<code>
if <bool:condition>
  ... statement block ...
endif
</code>

===== Arguments =====

^  Name  ^  Type  ^ Comment ^
|  //condition//  |  bool  | The condition that determines whether the statement block is to be executed. If true, the blcok is executed, and if false, execution skips to the matching endif/elseif/else statement that terminates the statement block.|

===== Example =====

<code>
int i
set i 5


if <islt i 0>
  echo "negative number"
elseif <iseq i 0>
  echo "zero"
else
  echo "positive number"
endif
</code>

===== Comments =====

==== Terminating an 'if' statement block ====

''If'' statements in ZeoScript will conditionally execute a block of code that is explicitly terminated by an ''elsif'', ''else'' or ''endif'' statement. 

Each ''if'' statement //must// be closed by a single matching ''endif'' statement. Optionally, the ''if'' statement may be followed by multiple ''elseif'' statements, and/or one ''else'' statement. The ''else'' statement must be the final conditional statement before the terminating ''endif'' statement. 

==== 'Else' after 'if' ====

ZeoScript differs from C/C++ and some other programming languages in that ''if'', ''else'' and ''elseif'' statements are explicitly block statements. In C/C++, for instance, you can omit the block { parens } after an if statement if you only want the next statement to be executed. Not so in ZeoScript; all ''if'', ''else'' and ''elseif'' statements must be explicitly closed.

**Wrong:**

<code>
if <islt i 0>
  echo "negative number"
else                  // error, else not terminated by endif
if <iseq i 0>
  echo "zero"
else
  echo "positive number"
endif
</code>

This code will result in the following error:

<file>
ZeoScript error: Cannot find matching 'endif' for 'else' statement.
 - Line 3: 'else'

ZeoScript compilation aborted on line 3 following errors.
</file>

**Right:**

<code>
if <islt i 0>
  echo "negative number"
else                  // now the else is terminated by 'endif', and contents are nested
  if <iseq i 0>
    echo "zero"
  else
    echo "positive number"
  endif
endif
</code>

**Better:**

<code>
if <islt i 0>
  echo "negative number"
elseif <iseq i 0>            // using the elseif statement, rather than nested else/if
  echo "zero"
else
  echo "positive number"
endif
</code>

===== See also =====

  * [[plugins:general:zeoscript:reference:functions:elseif]]
  * [[plugins:general:zeoscript:reference:functions:else]]
  * [[plugins:general:zeoscript:reference:functions:endif]]