Variables
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Variables

To do anything useful, you need to be able to store values in temporary locations and perform manipulations on them. We all know these as "variables." Perl actually has several kinds of variables, known more generically as "data structures." We'll use word "variable" to talk about a specific instance of a data structure (or "data type"). Some data types you may be familiar with: All of the above are "strongly typed," which means you must explicitly declare variables before you use them. Languages such as lisp or smalltalk do not work this way - data types are determined dynamically, and if a variable holds a number, the programmer is responsible for making sure that the program doesn't try to pull substrings out of it. All languages have internal representations for the different data types, they just vary in how much the programmer assists in making sure the variable is in the right form.

Perl falls in the middle. Which data type you use explicit in how you access it, but you don't need to declare it before you use it.


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The National Center for Supercomputing Applications

University of Illinois at Urbana-Champaign

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Last modified: June 19, 1997



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