Part I Introduction Scalar Data Variables Operators If Else Control Structures While Control Structures Standard Input Lists and Arrays Perl 1 Created by Larry Wall in 1987 Stable Release Perl 5 10 1 Two basic scalar data types Numbers and Strings Numbers Strings Integers and Floating Point Numbers have the same format Sequences of Characters Can either be enclosed in single or double quotes Ex v 8 value of 8 Ex v a value of a v contains v contains Undef For Numbers or Strings there is a special value called undef This is initially assigned to all variables and acts as a zero for numbers and a null or empty string for strings A scalar variable holds a single scalar value Names of any scalar variable must begin with the symbol followed by a Perl identifier Ex tom cs265 Assignment Arithmetic String Numeric Comparison String Comparison Ex cs 265 Ex c a b Addition c a b Subtraction c a b Multiplication c a b Division x dot String Concatenation Ex cl class ro room cl ro classroom x String Multiplier Ex cl x 2 classclass eq ne lt gt le ge 1 Interpolation of scalars into strings Any scalar variable inside a double quoted string is replaced by its value Ex example example print example prints example 2 Automatic conversion between numbers and strings Arguments of an arithmetic operator are automatically recognized as numbers and arguments of a string operator as strings Ex one 1 two 2 print one two prints 2 print one x two prints 11 print one two prints 12 Conditional Loop if else expected apple given pear if expected eq given print Apple else print Other Fruit Conditional Loop while num 1 while num 1111 num num Input in Perl is very convenient STDIN Ex Typical Line of Code for input line STDIN read a full line from standard input and store it in variable line line STDIN if line eq n print This was an empty line n else print This line was not empty n Lists are also user friendly in Perl List Literals representations of lists Ex 1 2 3 4 a list consisting of numbers 1 2 4 Ex 1 10 the same list as the one above now created by the range operator a b the range determined by current values of a and b List Assignment Examples Arrays are variables storing lists num 1 100 creates an array num with a numbers 1 through 100 print num 0 prints out 1 print num num prints out the largest index of the array
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