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PERL Script

Posted by admin in QTP Training on 10 4th, 2010 | 2 responses

PERL Script

Chapter-1 (Introduction)

Scripting Languages VsProgrammingLanguages

Scripting Language Programming Language

1) It is an Interpreter based Language 1) It is a compiler based Language.

2) Interpreter converts highlevelinstructions into machine

language line by line

2) Compiler converts the whole program in singleshort into machine language.

3) It doesnt create executable file. 3) It Creates .exe file.4) No need to compile the program Need to compile the program

5) It takes less code 4) It takes numerous lines of code

6) It greatly reduces development time 5) It increases development time

7) It reduces maintenance of cost 7) It Increases maintenance of cost

PERL-Practical Extraction and Reporting Language

y Perl was originally developed by Larry Wall, a linguist working as a systems administrator for NASA,in 1987, as a general-purpose Unix scripting language to make report processing easier.

y Perl is a high-level, general-purpose, interpreted, dynamic Scripting language.y The home of perl is UNIXy Perl Inherited features from UNIX utilities (awk, sed, grep, Smalltalk, Lisp, C, C++, Pascal and UNIX

shell.

y Perl written in C language.y Perl is free software.y Perl is open source code.

o Perl is highly portable Language (supports 76+ Operating systems, Scripts developed in one

operating system allows to run on other operating system with/without modifications.)

o Perl supports oops concepts known as object oriented perl.

o Perl supports database connectivity.

o Perl has given CPAN (Comprehensive Perl Archive Network) modules.website is www.cpan.org

o Perl was originally developed for to do manipulations in the text files later it is used in wide range of

the following areas

System Administration


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Database Administration

Network Programming

Web Development

Software Testing

Hardware Testing

Telecom

Vlsi

Baoinformatics and so on

o It is built-in with UNIX and Its flavers like Linux, Solaris etc

o Perl is a case sensitive Language.

o Each and every statement should end with (;) semicolon.

o Perl is an interpreter based Language.

o Extension of perl program is .pl or .plx

o Perl supports two types of comments.

Single line comment (#)

Multi line comment

Pod (perl old document)

Cut

Perl program compilation Process:

Writing a program to display welcome message

#! C:perlbinperl

print welcome to Perl n;


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print This is my first program;

Save with first.pl

Running perl Program in Windows

C:perl first.pl

#! It is shebang statement, used for to invoke perl interpreter path.

Running perl Program in UNIX/Linux

$ which perl # it displays location of perl

usr/bin/perl

perl v # version of perl

$ man perl # help document

$ vi first.pl

#! usr/bin/perl

print welcome to Perl n;

print This is my first program;

$ perl first.pl

or

$ chmod 755 first.pl

$./first.pl

Chapter-2 (Variables)

Variables

y It is a Data name or memory location name.y It is used for to store data value.y Value can change during execution of the programy It is a temporary storage location.y Perl allows implicit variable declaration.y Every variable occupies memory at runtime.


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Variables are classified into 3 types

y Scalar Variablesy Array Variables or List Variablesy Hash Variables or Associate Array Variables

1) Scalar Variables

y It holds one value.y The value may be Integer or Float or String.y The Variable should begin with $ symbol.

a=10; wrong

$a=10; right

2) Array Variables

o It is a group of scalar values

o It should begin with @ symbol.

3) Hash Array Variables

y It is a group of key pair values.y It should begin with % symbol.

1) Scalar Variables

$a=10; # Integer

$b=1.5; # Float

$c=Gcreddy #String

$d=perl is a scripting language # String

$e=100 # String

$f=Perl # String

Strings are classified into 3 types

1) Double quoted strings ( ) or qq with delimiter of any one || or [] or {} or

2) Single quoted strings ( ) or q with delimiter of any one || or [] or {} or


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3) Back tick / quoted strings (` `) or qx with delimiter of any one || or [] or {} or

a) $str=perl;

$x= I like $str;

print $x;

Output: I like Perl

b) $x= I like $str;

print $x

Output: I like $str

c) $x= I like perl n $str

print $x;

output: I like

Perl

d) $x= I like n $str;

print $x;

output: I like $x;

e) $str= I said Dont write to disk; # wrong

$str= I said |Dont write to disk|; # right

$str= I said Dont write to disk; # wrong

$str= I said Don|t write to disk; # right

$str= qq| I said Don|t write to disk|; # right

$str= q|I said Dont write to disk|; # right

f) $x= Unix/Linux; # right

$x= qq|Unix/Linux|; # wrong

$x= qq|Unix/Linux|; # right


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$x= qq{Unix/Linux}; # wrong

note: qq for variable substitute

q for as it is

qx for OS command

# $x= `dir`;

`md xyz`;

$x= qx|dir|;

print $x;

perl c pl.pl # compilation ok

Writing output:

Perl p1.pl>a1 # over write

Perl p1.pl>>a2 # add

Perl p1.pl> D:a3 # path

Standard Input / Output Handlers

print () it used for to write data to the screen

print(Hello);

or

print Hello;

or

print STDOUT Hello;

I/O handlers

1) STDIN

2) STDOUT

3) STDERR


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STDIN It used for to accept input from user

Ex: write a program accepting name and display?

Print What is your name;

$name=; or # Diamond operator

print Hello $name, Good morning;

chmod ($name); # It is a pre-defined function, it deletes the given string lost line character if it is new line.

Ex2: write a program accept 2 integer values and find sum?

Print Enter a number 1: ;

Chomp ($a= );

Print Enter a number 2: ;

Chomp ($b= );

$c= $a + $b

print n $a + $b= $c;

Chapter-3 (Operators)

1) Arithmetic Operators:

+, -, *, /, %, ** (right to left)

a) $a=10;

$b=20;

print $a + $b;

output: 30

b) $a=10;

$b=25abc;

print $a + $b;


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output: 35

a) $a=10;

$b=abc20;

print $a + $b;

output: 10

d) $a=10;

$b=20abc34;

print $a + $b;

output: 30

e) $a=perl;

$b=gcreddy;

print $a + $b;

output: 0

f) $a=10;

$b=25abc;

print $a + $b;

output: 35

print $a .$b;

output: 1025abc

g) $a=2;

$b=3;

print $a ** $b;

output: 8

h) $a=2;


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$b=3;

$c=2;

print $a ** $b ** $c;

output: 512

i) $a=2;

$b=3;

$c=2;

print ($a ** $b) ** $c;

output: 64

2) Relational Operators:

i) Numeric Comparison Operators

, =, ==, !=,

ii)String Comparison Operators

lt, gt, le, ge, eq, ne, cmp

a) $a=100;

$b=20;

$a>$b;

output: true

$a gt $b;

output: false (ansii nos)

b) $x= tecno;

$y= harika;

$x gt $y;

output: true


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$x > $y;

output: false (0,0)

c) $a=100;

$b=20;

$c= $a$b

if a>b output is 1

ay output is 1

x


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($a, $b, $c) = (10,20,30);

5) String Multiplication Operators:

(x)

Ex: $str=perl;

$k= $str x 5;

print $k;

output: perl perl perl perl perl

ex2: print -; x 50

output: -

ex3: print _; x 50

output: _________________________________________________

6) Range Operators:

(..)

1..10 # 12345678910

a..z #abcdefghijklmnopqrstuvwxyz

h..t # hijklmnopqrst

-10..1 #-10-9-8-7-6-5-4-3-2-101

10..1 # wrong

-1..-10 # wrong

z..a # wrong

7) String concatenation Operators:

(.)

It is used for to join two or more strings

$str= Load;


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$str=$str. ing;

Short hand Assignment Operators:

+=, -=, *=, /=, %=, .=, x=

$a-10;

$a= $a+5;

(or)

$a+=5;

9) Conditional Operators or Ternary operators:

(?:)

expression 1 ? expression 2 : expression 3

$a=100;

$b=99;

$a > $b ? print $a is big : print $b is big;

10) Incremental Operator (++)

$a=10;

$a=$a+1; or $a+=1; or $a++;

11) Detrimental Operators ()

$a=$a-1; or $a-=1 or $a;

-****-****

Chapter-4 (Control flow statements)a) Conditional Statements:

1) Simple if condition

if (condition)


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{

Statements

}

Statements

2) Simple unless

unless (condition)

{

Statements

}

Statements

3) If.else

if (condition)


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{

Statements

}

else

{

Statements

}

Statements

4) unless.else

unless (condition)

{

Statements


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}

else

{

Statements

}

Statements

5) if.elseifelse

if (condition)

{

Statements

}

else if (condition)

{

Statements


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}

else if (condition)

{

Statements

}

else

{

Statements

}

Statements

6) Single line if statement

statement if (condition);

Statements


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7) Single line unless statement

statement unless (condition);

Statements

b) Loop Statements:

1)While Loop

while (condition)

{

Statements

}

Statements

2) until Loop

until (condition)

{


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Statements

}

Statements

3) Dowhile Loop

do

{

Statements

}

while (condition)

{

Statements

}


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4) Do until Loop

do

{

Statements

}

until (condition)

{

Statements

}

5) For Loop

for (initiation; condition; increment/decrement)

{

Statements

}

Statements


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6) For Each Loop

foreach variable (list of variables)

{

Statements

}

Statements

7) Last keyword:

It is used for to terminate the loop; it is same as break in C Language.

While (condition)

{

Statements

last;


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}

Statements

Next keyword:

It is a keyword, used for to place control at beginning of the loop. It is same as continue in C language.

While (condition)

{

Statements

next;

}

Statements

Examples:

1) Write a program accepting a number and check given number is 3 digit number or not?


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Print Enter a number: ;

Chomp ($n= );

If ($n >=100 && $a


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$num=1;

while ($num ,=10)

{

print $num n;

$num++

}

(or)

for ($num=1; $num


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print ;

}

Note: $_ is Perl special and default variable. If we dont declare any variable for reading data then Perl will

store the value in default variable.

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