[Web4lib] global variables versus local variables

[John Fitzgibbon]

Hi,

When programming and when writing scripts, we are encouraged to use
variables that are local in scope whenever we can.

However, defining a variable within a sub-routine, as in VbScript, means
the variable is defined every time the sub-routine is run whereas
defining it outside the sub-routine means the variable is defined only
once. Why is it more efficient to define a variable within a
sub-routine?

Also, defining a variable within a loop causes the variable to be
defined afresh with each instance of the loop. Again this appears
inefficient but is generally done when a 'for loop' is run in
JavaScript.

I don't doubt that local variables have their uses; I'm simply seeking
an explanation.

Regards
John

John Fitzgibbon

John Fitzgibbon

Galway Public Library
Island House
Cathedral Square
Galway
Ireland

p: 00 353 91 562471
f: 00 353 91 565039
w: http://www.galwaylibrary.ie 

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