====== isdef ======

===== Description =====

Test whether a named variable exists.

===== Function prototype =====

<code>
bool isdef <string:VarName>
</code>

===== Arguments =====

^ Name ^ Type ^ Comment ^
| VarName | string | The name of a variable, the existence of which is to be tested.|

===== Return value =====

True if the variable named by //VarName// exists, and false otherwise.



===== Example =====

<code>
// create a variable called "i" and then test whether it exists using isdef and echo
int i

if <zs:isdef "i">
  echo "true"
else
  echo "false"
endif
</code>

... the output of which is written to the event log by [[plugins:general:zeoscript:reference:functions:echo]] as:

<file>
true
</file>

===== Comments =====

None.


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

  * [[plugins:general:zeoscript:reference:functions:new]]
  * [[plugins:general:zeoscript:reference:functions:del]]