static -- preserves the value of a variable between calls to a subroutine

 
sub foo() 

  static a 

  ... 

end sub 

The static keyword can be used within subroutines to mark variables as static. This has two effects: First, the variable is local to the subroutine, i.e. its value is not know outside the subroutine (this is the effect of the local keyword). Second, the static-keyword arranges things, so that the variable keeps its value between invocations of the subroutine (this is different from the local-keyword).

foo() 
foo() 
foo() 

sub foo() 
	static a 
	local b 
	a=a+1 
	b=b+1 
	print a,b 
end sub 

This program shows the difference between static and local variables within a subroutine; it produces this output:


1 1 
2 1 
3 1 


The output shows, that the static variable a keeps its value between subroutine calls, whereas b is initialized with the value 0 at every call to the subroutine foo.