Noob trying to improve Post: 302989485

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Operating Systems OS X (Apple) Noob trying to improve Post 302989485 by bakunin on Friday 13th of January 2017 08:31:37 AM

01-13-2017

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Quote:

Originally Posted by Ardzii

I knew that declaring the variable so that it can be used elsewhere. However, in the course I'm taking they didn't extend on the value added of it.

There is more about declaring variables, as there is more about programming than just making it work correctly: well written programs work correctly as well as badly written programs (everything else is NOT a program but a mess) but a well written program will also be easy to understand, therefore easy to maintain and well documented (this plays up the same alley as "easy to understand"). What is "well written" versus "badly written" shows not always immediately but usually when trying to create version 10 from version 9. This is true for every programming language and every programming paradigma. Whatever the technology you use: strive to write well-written programs.

To declare variables has several values: first, you can assign sensible initial values so that you lessen the risk of using a variable before you are ready to use it. Second, declaring the variables up front builds automatically a sort-of "data dictionary" so that you quasi-automatically describe to yourself what you are using to variable for, what it is expect to hold, etc.. You build up a common point of reference that way and once your script became several hundred lines long and you have just used it for some months instead of rewrite it you will be thankful to yourself for the explanations to your thoughts you have left.

Programming is about organising your thoughts and the better you organise them the better the results are.

Quote:

Originally Posted by Ardzii

I see that you used local (which I had not seen yet) rather than declare (this was the one I knew about): Any particular reason? Regarding the "-i" I guess it stands for integer?

Yes, "-i" is for integer. Regarding the hiccup between "local" and "declare": probably "declare" is correct. I don't use bash much, so you can safely assume that to be my error, not yours.

I hope this helps.

bakunin

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LEARN ABOUT REDHAT

set

set(n)							       Tcl Built-In Commands							    set(n)

__________________________________________________________________________________________________________________________________________________

NAME

       set - Read and write variables

SYNOPSIS

       set varName ?value?
_________________________________________________________________

DESCRIPTION

       Returns	the  value  of	variable  varName.   If value is specified, then set the value of varName to value, creating a new variable if one
       doesn't already exist, and return its value.  If varName contains an open parenthesis and ends with a close parenthesis, then it refers	to
       an  array  element:  the characters before the first open parenthesis are the name of the array, and the characters between the parentheses
       are the index within the array.	Otherwise varName refers to a scalar variable.	Normally, varName is unqualified  (does  not  include  the
       names of any containing namespaces), and the variable of that name in the current namespace is read or written.	If varName includes names-
       pace qualifiers (in the array name if it refers to an array element), the variable in the specified namespace is read or written.

       If no procedure is active, then varName refers to a namespace variable (global variable if the current namespace is the global  namespace).
       If  a  procedure  is active, then varName refers to a parameter or local variable of the procedure unless the global command was invoked to
       declare varName to be global, or unless a variable command was invoked to declare varName to be a namespace variable.

SEE ALSO

       expr(n), proc(n), trace(n), unset(n)

KEYWORDS

       read, write, variable

Tcl																	    set(n)