exists

checks variable existence

Calling Sequence

ve = exists(name [,where])

Arguments

ve Output result with possible values:  1 if true, 0 if false

: :name a character string : :where an optional character with possible values: ‘l’ (local),

‘n’ (nolocal) and ‘a’ (all). The default value is ‘a’.

:

Description

exists(name) returns 1 if the variable named name exists and 0 otherwise.

Caveats: a function which uses exists may return a result which depends on the environment!

exists(name,’l’) returns 1 if the variable named name exists in the environment of the current function and 0 otherwise.

exists(name,’n’) returns 1 if the variable named name exists in any level of the calling environment (including the Scilab shell main level) of the current function and 0 otherwise.

Warning: the exists function does not check if a variable exists in the global namespace.

Examples

exists("myNotLikelyToExistVariable")
myNotLikelyToExistVariable = 1;
exists("myNotLikelyToExistVariable")

`deff`_('foo(x)',..
['disp([exists(''a12''),exists(''a12'',''l'')])'
 'disp([exists(''x''),exists(''x'',''l'')])'])
foo(1)
a12=[];foo(1)

function level1()
  function level2()
    `disp`_(exists("a","a"));
    `disp`_(exists("a","l"));
    `disp`_(exists("a","n"));
  endfunction
  level2()
endfunction
function go()
  a=1;
  level1()
endfunction
go()

See Also

• isdef checks variable existence
• isglobal check if a variable is global
• whereis name of library containing a function
• type Returns the type of a variable
• typeof object type
• macrovar variables of function