Jun 12th 2014
Coding 101 21
Perl: Getting Started
Hosted by
Fr. Robert Ballecer, SJ,
Shannon Morse
Perl installation.
Although the show is no longer in production, you can enjoy episodes from the TWiT Archives.
Guests:
Patrick Delahanty
Ivory Tower
Control Structures
- The structure of Perl is more like C# than Python
- While Python uses white-space to delineate lines of code, Perl uses ";" a semicolon
- Also like C#, Perl uses "{}" Curly brackets to create BLOCKS of code Variables
- Much like Python, Perl doesn't require you to declare variables separately from expressions.
- You can declare variable WITHIN the expression.
- Perl offers three types of variables: Scalars, Arrays and Associative Arrays
- We're going to show you the first two: Scalars and Arrays
Printing in Perl
- Printing in Perl works much in the same way as printing in Python
- You can print numbers, strings, variables, and combinations thereof.
Scalars
- These are either numbers or strings
- Perl doesn't require you to mark a variable as either a number or a string... it all looks the same to Perl
- Perl also doesn't require you to differentiate between integers and real numbers
Usage of Scalars:
- You declare a scalar variable by using "$" right before the name of the variable
- $Var1 = 28 creates a variable named "Var1" containing the integer "4"
- $Var2 = "Coding 101" creates a variable named "Var2" containing the string "Coding 101"
- $Var3 = 3.14 creates a variable named "Var3" containing the decimal number "4.5"
Arrays
- An array is a ONE-DIMENSIONAL indexed list of Scalar variables
Usage of Arrays
- You declare an array by using "@" right before the name of the array
- Individual scalar variables within the array can be accessed by pointing to their index with the SCALAR identifier
- @C101 = ("Padre", "Snubs", "Bryan") creates an array named "C101" and fills it with the strings, "Padre", "Snubs" and "Bryan"
- @coding = @C101 creates an array called, "coding" and fills it with the values from the array "C101"
- $C101[2] = "Cranky Hippo" changes the value in the third item in the array "C101" from "Bryan" to "Cranky Hippo"
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