Introduction

• know why we place #!/usr/local/bin/perl at the beginning of a Perl script; what is the default action taken by UNIX if we don't?
• do not worry about using Perl at the command line (that is, things like perl -ne 'print' test.dat which doesn't run a script but rather executes the contents of the single quotes)

• know how a single-quoted string treats characters preceded by backslashes vs. how a double-quoted string treats them
• know how to use escape sequences to alter the case of subsequent characters in a double quoted string

• know the difference between numeric and string context and which operators invoke a particular context
• know what the string operators  . and  x  do (and their precedence)
• be able to convert a string to a number as Perl would

• what types of things can be stored in a scalar variable?
• what is the difference between $res = ++$num; vs. $res = $num++; (for numeric data)
• do not worry about ++ applied to strings
• what is variable interpolation?
• know how read from STDIN in scalar context
• what does chomp do?
• what does undef return in numeric context? in string context?

• what is a list literal ?
• be able to create a list using the list constructor operator (..)
• be able to create a list of strings using the quote word function
• know how to assign to an array using a list on the right-hand side
• know how to assign to a list of scalar variables from either a list or array
• understand what scalar context is vs. list context
• know how to access an individual element of an array
• what is an array slice?  know how to use a slice on the left- and right-hand side of an assignment
• how can you get the size of an array?  how can you get the index of the last element of an array?
• don't worry about negative array subscripts
• don't worry about push, pop, shift, and unshift (we didn't cover them in class)
• be comfortable using sort
• know how functions apply in scalar context and list context (e.g., reverse and chomp)
• know how to read an entire array at once from STDIN
• what is the result of variable interpolating an array?

• know the rules for determining true and false in Perl
• be comfortable with using comparison and logical operators to create conditional expressions
• recall that there are two sets of comparison operators -- one for numbers and one for strings
• be able to write nested if structures using elsif
• know the difference between a while {} and a do {} while
• be comfortable using for loops
• know how to use foreach; recall that this construct returns an alias to each list element rather than a copy

• what is a key? what is a value? can two distinct hash elements ((key,value) pairs) have the same key? can two distinct hash elements have the same value?
• know how to add elements to a hash and manipulate individual values
• what is used as the literal representation of a hash? know how to create a hash from this representation
• be able to create a hash using the "other comma" operator (=>)
• can a hash be variable interpolated?  what is a shortcut for printing the literal representation of a hash?
• know how to iterate through a hash using control structures and the following functions : keys, values, each; what does each of these functions do?
• how can you determine the size (number of elements) of a hash?
• know how to remove an element from a hash
• what is a hash slice?  be able to create or modify a hash using a hash slice; be able to use a hash slice on the left-hand side of an assignment

• to which variable does the diamond operator (<>) automatically make assignments?; know that a number of other Perl functions (e.g., chomp and print) can implicitly use this variable
• how does the diamond operator determine the files that it will read from
• what does the diamond operator do if no files are specified on the command line with the name of the Perl script
• be able to write code using the diamond operator
• do not worry about printf