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Introfuction to Perl

Introfuction to Perl

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  • 1. Let’s Learn PerlAn introduction to Perl Sreejith SNLP Process Analyst 365Media Pvt. Ltd.srssreejith@gmail.com January 22, 2011 Sreejith S Let’s Learn Perl
  • 2. Just a word about me !! Working in Natural Language Processing (NLP), Machine Learning, Data Mining Passionate about Free and Open source :-) Works for 365Media Pvt. Ltd. Coimbatore India. Sreejith S Let’s Learn Perl
  • 3. What’s Perl ?? Practical Extraction and Reporting Language Sreejith S Let’s Learn Perl
  • 4. What’s Perl ?? Practical Extraction and Reporting Language Perl is a Portable Scripting Language Sreejith S Let’s Learn Perl
  • 5. What’s Perl ?? Practical Extraction and Reporting Language Perl is a Portable Scripting Language Fast and easy text processing capability Sreejith S Let’s Learn Perl
  • 6. What’s Perl ?? Practical Extraction and Reporting Language Perl is a Portable Scripting Language Fast and easy text processing capability Fast and easy file handling capability Sreejith S Let’s Learn Perl
  • 7. What’s Perl ?? Practical Extraction and Reporting Language Perl is a Portable Scripting Language Fast and easy text processing capability Fast and easy file handling capability It aims to be practical (easy to use, efficient, complete) rather than beautiful (tiny, elegant, minimal) Sreejith S Let’s Learn Perl
  • 8. What’s Perl ?? Practical Extraction and Reporting Language Perl is a Portable Scripting Language Fast and easy text processing capability Fast and easy file handling capability It aims to be practical (easy to use, efficient, complete) rather than beautiful (tiny, elegant, minimal) Perl was developed by Larry Wall. Sreejith S Let’s Learn Perl
  • 9. To install... Perl Comes by Default on Linux, Cygwin, MacOSX Sreejith S Let’s Learn Perl
  • 10. To install... Perl Comes by Default on Linux, Cygwin, MacOSX www.perl.com has rpm’s for Linux Sreejith S Let’s Learn Perl
  • 11. To install... Perl Comes by Default on Linux, Cygwin, MacOSX www.perl.com has rpm’s for Linux www.activestate.com has binaries for Windows Sreejith S Let’s Learn Perl
  • 12. To install... Perl Comes by Default on Linux, Cygwin, MacOSX www.perl.com has rpm’s for Linux www.activestate.com has binaries for Windows Latest Version is 5.10 Sreejith S Let’s Learn Perl
  • 13. To install... Perl Comes by Default on Linux, Cygwin, MacOSX www.perl.com has rpm’s for Linux www.activestate.com has binaries for Windows Latest Version is 5.10 To check if Perl is working and the version number Sreejith S Let’s Learn Perl
  • 14. To install... Perl Comes by Default on Linux, Cygwin, MacOSX www.perl.com has rpm’s for Linux www.activestate.com has binaries for Windows Latest Version is 5.10 To check if Perl is working and the version number perl -v or perl -version Sreejith S Let’s Learn Perl
  • 15. Sreejith S Let’s Learn Perl
  • 16. Basic Syntax of Perl Comments Sreejith S Let’s Learn Perl
  • 17. Basic Syntax of Perl Comments begin with # Sreejith S Let’s Learn Perl
  • 18. Basic Syntax of Perl Comments begin with # dont try to use // or /* ... */ Sreejith S Let’s Learn Perl
  • 19. Basic Syntax of Perl Comments begin with # dont try to use // or /* ... */ Print Sreejith S Let’s Learn Perl
  • 20. Basic Syntax of Perl Comments begin with # dont try to use // or /* ... */ Print print is simple function to display/output something on monitor/stdout Sreejith S Let’s Learn Perl
  • 21. Basic Syntax of Perl Comments begin with # dont try to use // or /* ... */ Print print is simple function to display/output something on monitor/stdout e.g :- print “hello world“; Sreejith S Let’s Learn Perl
  • 22. Basic Syntax of Perl Comments begin with # dont try to use // or /* ... */ Print print is simple function to display/output something on monitor/stdout e.g :- print “hello world“; Statement terminator ; Sreejith S Let’s Learn Perl
  • 23. Basic Syntax of Perl Comments begin with # dont try to use // or /* ... */ Print print is simple function to display/output something on monitor/stdout e.g :- print “hello world“; Statement terminator ; All Statements end with ; like C language Sreejith S Let’s Learn Perl
  • 24. Basic Syntax of Perl Comments begin with # dont try to use // or /* ... */ Print print is simple function to display/output something on monitor/stdout e.g :- print “hello world“; Statement terminator ; All Statements end with ; like C language Delimiter Sreejith S Let’s Learn Perl
  • 25. Basic Syntax of Perl Comments begin with # dont try to use // or /* ... */ Print print is simple function to display/output something on monitor/stdout e.g :- print “hello world“; Statement terminator ; All Statements end with ; like C language Delimiter {} delimit blocks, loops, subroutines Sreejith S Let’s Learn Perl
  • 26. Basic Syntax of Perl Comments begin with # dont try to use // or /* ... */ Print print is simple function to display/output something on monitor/stdout e.g :- print “hello world“; Statement terminator ; All Statements end with ; like C language Delimiter {} delimit blocks, loops, subroutines No main() function Sreejith S Let’s Learn Perl
  • 27. Basic Syntax of Perl Comments begin with # dont try to use // or /* ... */ Print print is simple function to display/output something on monitor/stdout e.g :- print “hello world“; Statement terminator ; All Statements end with ; like C language Delimiter {} delimit blocks, loops, subroutines No main() function Top-down programming approach Sreejith S Let’s Learn Perl
  • 28. Structure of a Perl Program #! /usr/bin/perl -w Sreejith S Let’s Learn Perl
  • 29. Structure of a Perl Program #! /usr/bin/perl -w It tells where to find Perl Sreejith S Let’s Learn Perl
  • 30. Structure of a Perl Program #! /usr/bin/perl -w It tells where to find Perl .pl extension is optional but is commonly used Sreejith S Let’s Learn Perl
  • 31. Structure of a Perl Program #! /usr/bin/perl -w It tells where to find Perl .pl extension is optional but is commonly used You can write perl programs without extension also. Sreejith S Let’s Learn Perl
  • 32. Structure of a Perl Program #! /usr/bin/perl -w It tells where to find Perl .pl extension is optional but is commonly used You can write perl programs without extension also. -w switches on warning : not required but a really good idea Sreejith S Let’s Learn Perl
  • 33. Customary Hello World Program #! /usr/bin/perl -w print "Hello World!n"; Sreejith S Let’s Learn Perl
  • 34. Customary Hello World Program #! /usr/bin/perl -w print "Hello World!n"; Save this as hello.pl Sreejith S Let’s Learn Perl
  • 35. Customary Hello World Program #! /usr/bin/perl -w print "Hello World!n"; Save this as hello.pl To run the program Sreejith S Let’s Learn Perl
  • 36. Customary Hello World Program #! /usr/bin/perl -w print "Hello World!n"; Save this as hello.pl To run the program perl hello.pl or perl hello Sreejith S Let’s Learn Perl
  • 37. Variables Variables are memory location to store information. Sreejith S Let’s Learn Perl
  • 38. Variables Variables are memory location to store information. Variables are type less Sreejith S Let’s Learn Perl
  • 39. Variables Variables are memory location to store information. Variables are type less There is no data type like int,char,float Sreejith S Let’s Learn Perl
  • 40. Variables Variables are memory location to store information. Variables are type less There is no data type like int,char,float Variables do not need to be declared Sreejith S Let’s Learn Perl
  • 41. Variables Variables are memory location to store information. Variables are type less There is no data type like int,char,float Variables do not need to be declared Every variable is a string Sreejith S Let’s Learn Perl
  • 42. Variables Variables are memory location to store information. Variables are type less There is no data type like int,char,float Variables do not need to be declared Every variable is a string Variable type is decided at run time Sreejith S Let’s Learn Perl
  • 43. Variables Variables are memory location to store information. Variables are type less There is no data type like int,char,float Variables do not need to be declared Every variable is a string Variable type is decided at run time Depending on the context will be treated as int, float etc. Sreejith S Let’s Learn Perl
  • 44. Variables Variables are memory location to store information. Variables are type less There is no data type like int,char,float Variables do not need to be declared Every variable is a string Variable type is decided at run time Depending on the context will be treated as int, float etc. There are 4 kinds of variables namely Sreejith S Let’s Learn Perl
  • 45. Variables Variables are memory location to store information. Variables are type less There is no data type like int,char,float Variables do not need to be declared Every variable is a string Variable type is decided at run time Depending on the context will be treated as int, float etc. There are 4 kinds of variables namely Scalars Sreejith S Let’s Learn Perl
  • 46. Variables Variables are memory location to store information. Variables are type less There is no data type like int,char,float Variables do not need to be declared Every variable is a string Variable type is decided at run time Depending on the context will be treated as int, float etc. There are 4 kinds of variables namely Scalars Lists Sreejith S Let’s Learn Perl
  • 47. Variables Variables are memory location to store information. Variables are type less There is no data type like int,char,float Variables do not need to be declared Every variable is a string Variable type is decided at run time Depending on the context will be treated as int, float etc. There are 4 kinds of variables namely Scalars Lists Arrays Sreejith S Let’s Learn Perl
  • 48. Variables Variables are memory location to store information. Variables are type less There is no data type like int,char,float Variables do not need to be declared Every variable is a string Variable type is decided at run time Depending on the context will be treated as int, float etc. There are 4 kinds of variables namely Scalars Lists Arrays Hashes. Sreejith S Let’s Learn Perl
  • 49. Scalars Scalar meaning single value Sreejith S Let’s Learn Perl
  • 50. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. Sreejith S Let’s Learn Perl
  • 51. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or Sreejith S Let’s Learn Perl
  • 52. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or Sreejith S Let’s Learn Perl
  • 53. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Sreejith S Let’s Learn Perl
  • 54. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right Sreejith S Let’s Learn Perl
  • 55. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Sreejith S Let’s Learn Perl
  • 56. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong Sreejith S Let’s Learn Perl
  • 57. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong $24da, $hi&bye, $bar$foo Sreejith S Let’s Learn Perl
  • 58. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong $24da, $hi&bye, $bar$foo Examples Sreejith S Let’s Learn Perl
  • 59. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong $24da, $hi&bye, $bar$foo Examples $name=”ram”; Sreejith S Let’s Learn Perl
  • 60. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong $24da, $hi&bye, $bar$foo Examples $name=”ram”; # in string context Sreejith S Let’s Learn Perl
  • 61. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong $24da, $hi&bye, $bar$foo Examples $name=”ram”; # in string context $age=30; Sreejith S Let’s Learn Perl
  • 62. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong $24da, $hi&bye, $bar$foo Examples $name=”ram”; # in string context $age=30; # in numerical context Sreejith S Let’s Learn Perl
  • 63. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong $24da, $hi&bye, $bar$foo Examples $name=”ram”; # in string context $age=30; # in numerical context $value = 4.43; Sreejith S Let’s Learn Perl
  • 64. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong $24da, $hi&bye, $bar$foo Examples $name=”ram”; # in string context $age=30; # in numerical context $value = 4.43; # in float context Sreejith S Let’s Learn Perl
  • 65. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong $24da, $hi&bye, $bar$foo Examples $name=”ram”; # in string context $age=30; # in numerical context $value = 4.43; # in float context $foo = Z; Sreejith S Let’s Learn Perl
  • 66. Scalars Scalar meaning single value Name of scalar variable must begin with $ symbol. next character must a letter or remaining characters: letters, numbers, or name can be up to 255 characters long Right $foo, $a, $zebra1, $F87dr df3 Wrong $24da, $hi&bye, $bar$foo Examples $name=”ram”; # in string context $age=30; # in numerical context $value = 4.43; # in float context $foo = Z; # in char context Sreejith S Let’s Learn Perl
  • 67. Variable & Character Interpolation Perl looks for variables inside strings and replaces them with their value Sreejith S Let’s Learn Perl
  • 68. Variable & Character Interpolation Perl looks for variables inside strings and replaces them with their value $name = "Sree"; print "$name is my namen"; Sreejith S Let’s Learn Perl
  • 69. Variable & Character Interpolation Perl looks for variables inside strings and replaces them with their value $name = "Sree"; print "$name is my namen"; This does not happen when you use single quotes Sreejith S Let’s Learn Perl
  • 70. Variable & Character Interpolation Perl looks for variables inside strings and replaces them with their value $name = "Sree"; print "$name is my namen"; This does not happen when you use single quotes print ’$name is my name’; and it will print Sreejith S Let’s Learn Perl
  • 71. Variable & Character Interpolation Perl looks for variables inside strings and replaces them with their value $name = "Sree"; print "$name is my namen"; This does not happen when you use single quotes print ’$name is my name’; and it will print $name is my name Sreejith S Let’s Learn Perl
  • 72. Variable & Character Interpolation Perl looks for variables inside strings and replaces them with their value $name = "Sree"; print "$name is my namen"; This does not happen when you use single quotes print ’$name is my name’; and it will print $name is my name List of character escapes that are recognized when using double quoted strings All escape characters are recognized Sreejith S Let’s Learn Perl
  • 73. Variable & Character Interpolation Perl looks for variables inside strings and replaces them with their value $name = "Sree"; print "$name is my namen"; This does not happen when you use single quotes print ’$name is my name’; and it will print $name is my name List of character escapes that are recognized when using double quoted strings All escape characters are recognized print "Hello World!n"; # It prints Hello World and then a return Sreejith S Let’s Learn Perl
  • 74. Lists List variables are denoted by symbol ‘()‘ Sreejith S Let’s Learn Perl
  • 75. Lists List variables are denoted by symbol ‘()‘ List is just a list of values may be constants, scalars etc Sreejith S Let’s Learn Perl
  • 76. Lists List variables are denoted by symbol ‘()‘ List is just a list of values may be constants, scalars etc (a,b,c) or ($name,$age,$sex) Sreejith S Let’s Learn Perl
  • 77. Lists List variables are denoted by symbol ‘()‘ List is just a list of values may be constants, scalars etc (a,b,c) or ($name,$age,$sex) The index are specified inside a square bracket ‘[]‘ Sreejith S Let’s Learn Perl
  • 78. Lists List variables are denoted by symbol ‘()‘ List is just a list of values may be constants, scalars etc (a,b,c) or ($name,$age,$sex) The index are specified inside a square bracket ‘[]‘ $first=(a,b,c)[0]; print "$firstn"; Sreejith S Let’s Learn Perl
  • 79. Lists List variables are denoted by symbol ‘()‘ List is just a list of values may be constants, scalars etc (a,b,c) or ($name,$age,$sex) The index are specified inside a square bracket ‘[]‘ $first=(a,b,c)[0]; print "$firstn"; List variables can be assigned like this Sreejith S Let’s Learn Perl
  • 80. Lists List variables are denoted by symbol ‘()‘ List is just a list of values may be constants, scalars etc (a,b,c) or ($name,$age,$sex) The index are specified inside a square bracket ‘[]‘ $first=(a,b,c)[0]; print "$firstn"; List variables can be assigned like this ($name,$age)=(’Raman’,20); print "name=$namen"; Sreejith S Let’s Learn Perl
  • 81. Arrays Array variables should have prefix ‘@‘ Sreejith S Let’s Learn Perl
  • 82. Arrays Array variables should have prefix ‘@‘ Arrays are used to store ordered values Sreejith S Let’s Learn Perl
  • 83. Arrays Array variables should have prefix ‘@‘ Arrays are used to store ordered values Much more dynamic than C/C++ Sreejith S Let’s Learn Perl
  • 84. Arrays Array variables should have prefix ‘@‘ Arrays are used to store ordered values Much more dynamic than C/C++ no declaration of size, type Sreejith S Let’s Learn Perl
  • 85. Arrays Array variables should have prefix ‘@‘ Arrays are used to store ordered values Much more dynamic than C/C++ no declaration of size, type can hold any kind of value, and multiple kinds of values Sreejith S Let’s Learn Perl
  • 86. Arrays Array variables should have prefix ‘@‘ Arrays are used to store ordered values Much more dynamic than C/C++ no declaration of size, type can hold any kind of value, and multiple kinds of values Array Indexes start at 0 Sreejith S Let’s Learn Perl
  • 87. Arrays Array variables should have prefix ‘@‘ Arrays are used to store ordered values Much more dynamic than C/C++ no declaration of size, type can hold any kind of value, and multiple kinds of values Array Indexes start at 0 @array=(1,2,3); To access the whole array, use the whole array Sreejith S Let’s Learn Perl
  • 88. Arrays Array variables should have prefix ‘@‘ Arrays are used to store ordered values Much more dynamic than C/C++ no declaration of size, type can hold any kind of value, and multiple kinds of values Array Indexes start at 0 @array=(1,2,3); To access the whole array, use the whole array print @array; Sreejith S Let’s Learn Perl
  • 89. Arrays Array variables should have prefix ‘@‘ Arrays are used to store ordered values Much more dynamic than C/C++ no declaration of size, type can hold any kind of value, and multiple kinds of values Array Indexes start at 0 @array=(1,2,3); To access the whole array, use the whole array print @array; To access one element of the array : use $ Sreejith S Let’s Learn Perl
  • 90. Arrays Array variables should have prefix ‘@‘ Arrays are used to store ordered values Much more dynamic than C/C++ no declaration of size, type can hold any kind of value, and multiple kinds of values Array Indexes start at 0 @array=(1,2,3); To access the whole array, use the whole array print @array; To access one element of the array : use $ print $array[0]; # prints : 1 Sreejith S Let’s Learn Perl
  • 91. Operations on Arrays To append to the end of an array : PUSH Sreejith S Let’s Learn Perl
  • 92. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; Sreejith S Let’s Learn Perl
  • 93. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; To remove the last element of the array : POP Sreejith S Let’s Learn Perl
  • 94. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; To remove the last element of the array : POP @array=(1,2,3); $last=pop @array; print "last=$lastn"; Sreejith S Let’s Learn Perl
  • 95. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; To remove the last element of the array : POP @array=(1,2,3); $last=pop @array; print "last=$lastn"; To prepend to the beginning of an array : UNSHIFT Sreejith S Let’s Learn Perl
  • 96. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; To remove the last element of the array : POP @array=(1,2,3); $last=pop @array; print "last=$lastn"; To prepend to the beginning of an array : UNSHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; Sreejith S Let’s Learn Perl
  • 97. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; To remove the last element of the array : POP @array=(1,2,3); $last=pop @array; print "last=$lastn"; To prepend to the beginning of an array : UNSHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; To remove the first element of the array : SHIFT Sreejith S Let’s Learn Perl
  • 98. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; To remove the last element of the array : POP @array=(1,2,3); $last=pop @array; print "last=$lastn"; To prepend to the beginning of an array : UNSHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; To remove the first element of the array : SHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; Sreejith S Let’s Learn Perl
  • 99. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; To remove the last element of the array : POP @array=(1,2,3); $last=pop @array; print "last=$lastn"; To prepend to the beginning of an array : UNSHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; To remove the first element of the array : SHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; Sreejith S Let’s Learn Perl
  • 100. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; To remove the last element of the array : POP @array=(1,2,3); $last=pop @array; print "last=$lastn"; To prepend to the beginning of an array : UNSHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; To remove the first element of the array : SHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; Sreejith S Let’s Learn Perl
  • 101. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; To remove the last element of the array : POP @array=(1,2,3); $last=pop @array; print "last=$lastn"; To prepend to the beginning of an array : UNSHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; To remove the first element of the array : SHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; Sreejith S Let’s Learn Perl
  • 102. Operations on Arrays To append to the end of an array : PUSH @array=(1,2,3); push @array,’4’; print "@array n"; To remove the last element of the array : POP @array=(1,2,3); $last=pop @array; print "last=$lastn"; To prepend to the beginning of an array : UNSHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; To remove the first element of the array : SHIFT @array=(3,4,5); unshift @array,’2’; print "array=@arrayn"; Sreejith S Let’s Learn Perl
  • 103. Operations on Arrays Contind... $#array is a special variable containing index of last element. Sreejith S Let’s Learn Perl
  • 104. Operations on Arrays Contind... $#array is a special variable containing index of last element. print $#array; # it will print 2 Sreejith S Let’s Learn Perl
  • 105. Operations on Arrays Contind... $#array is a special variable containing index of last element. print $#array; # it will print 2 Another way to find the number of elements in the array: Sreejith S Let’s Learn Perl
  • 106. Operations on Arrays Contind... $#array is a special variable containing index of last element. print $#array; # it will print 2 Another way to find the number of elements in the array: $array_size = @array; scalar(@array) is a function to return the size of array Sreejith S Let’s Learn Perl
  • 107. Operations on Arrays Contind... $#array is a special variable containing index of last element. print $#array; # it will print 2 Another way to find the number of elements in the array: $array_size = @array; scalar(@array) is a function to return the size of array Sreejith S Let’s Learn Perl
  • 108. Hashes Hash variables will have % as prefix Sreejith S Let’s Learn Perl
  • 109. Hashes Hash variables will have % as prefix Key-Value pair Sreejith S Let’s Learn Perl
  • 110. Hashes Hash variables will have % as prefix Key-Value pair The contents of hash are called values and index is called key. the array: Sreejith S Let’s Learn Perl
  • 111. Hashes Hash variables will have % as prefix Key-Value pair The contents of hash are called values and index is called key. the array: %fruits= ( ’apple’=>’red’,’banana’=>’yellow’, ’grape’ =>’black’); print "colour of apple =$fruits{apple}n"; Sreejith S Let’s Learn Perl
  • 112. Hashes Hash variables will have % as prefix Key-Value pair The contents of hash are called values and index is called key. the array: %fruits= ( ’apple’=>’red’,’banana’=>’yellow’, ’grape’ =>’black’); print "colour of apple =$fruits{apple}n"; Other way of populating a hash Sreejith S Let’s Learn Perl
  • 113. Hashes Hash variables will have % as prefix Key-Value pair The contents of hash are called values and index is called key. the array: %fruits= ( ’apple’=>’red’,’banana’=>’yellow’, ’grape’ =>’black’); print "colour of apple =$fruits{apple}n"; Other way of populating a hash %fruits =(’apple’,’red’,’banana’,’yellow’, ’grape’,’black’); print "colour of banana =$fruits{banana}n"; Sreejith S Let’s Learn Perl
  • 114. Hashes Hash variables will have % as prefix Key-Value pair The contents of hash are called values and index is called key. the array: %fruits= ( ’apple’=>’red’,’banana’=>’yellow’, ’grape’ =>’black’); print "colour of apple =$fruits{apple}n"; Other way of populating a hash %fruits =(’apple’,’red’,’banana’,’yellow’, ’grape’,’black’); print "colour of banana =$fruits{banana}n"; Note the {} instead of [ ] as in the case of array; Sreejith S Let’s Learn Perl
  • 115. Conditionals - IF The if statement is similar to if in C language, except Sreejith S Let’s Learn Perl
  • 116. Conditionals - IF The if statement is similar to if in C language, except flower brace is required even for single statement else if is noted by elsif (note missing e) Sreejith S Let’s Learn Perl
  • 117. Conditionals - IF The if statement is similar to if in C language, except flower brace is required even for single statement else if is noted by elsif (note missing e) The syntax of if statement is Sreejith S Let’s Learn Perl
  • 118. Conditionals - IF The if statement is similar to if in C language, except flower brace is required even for single statement else if is noted by elsif (note missing e) The syntax of if statement is if (condition) { } elsif (condition){ } else { } Sreejith S Let’s Learn Perl
  • 119. Control Structures - Loops Perl supports four main loop types Sreejith S Let’s Learn Perl
  • 120. Control Structures - Loops Perl supports four main loop types while, until, for, and foreach Sreejith S Let’s Learn Perl
  • 121. Control Structures - Loops Perl supports four main loop types while, until, for, and foreach while loop is used to iterate and has syntax similar to C. Sreejith S Let’s Learn Perl
  • 122. Control Structures - Loops Perl supports four main loop types while, until, for, and foreach while loop is used to iterate and has syntax similar to C. $i = 0; while ( $i <= 1000 ) { print $in; $i++; } Sreejith S Let’s Learn Perl
  • 123. Control Structures - Until Loop The until function evaluates an expression repeatedly until a specific condition is met Sreejith S Let’s Learn Perl
  • 124. Control Structures - Until Loop The until function evaluates an expression repeatedly until a specific condition is met $i = 0; until ($i == 1000) { print $in; $i++; } Sreejith S Let’s Learn Perl
  • 125. Control Structures - For Loop For loop syntax is similar to c. Sreejith S Let’s Learn Perl
  • 126. Control Structures - For Loop For loop syntax is similar to c. There are variations Sreejith S Let’s Learn Perl
  • 127. Control Structures - For Loop For loop syntax is similar to c. There are variations Syntax 1: Sreejith S Let’s Learn Perl
  • 128. Control Structures - For Loop For loop syntax is similar to c. There are variations Syntax 1: for ( $i = 0; $i <= 1000; $i=$i+2 ) { print $i; } Sreejith S Let’s Learn Perl
  • 129. Control Structures - For Loop For loop syntax is similar to c. There are variations Syntax 1: for ( $i = 0; $i <= 1000; $i=$i+2 ) { print $i; } Syntax 2: Sreejith S Let’s Learn Perl
  • 130. Control Structures - For Loop For loop syntax is similar to c. There are variations Syntax 1: for ( $i = 0; $i <= 1000; $i=$i+2 ) { print $i; } Syntax 2: for $i(0..1000) { print $i; } Sreejith S Let’s Learn Perl
  • 131. Control Structures - ForEach Loop Syntax 3: Sreejith S Let’s Learn Perl
  • 132. Control Structures - ForEach Loop Syntax 3: foreach $i (a,b,c) { print uc $i; } Sreejith S Let’s Learn Perl
  • 133. Default scalar variable $ is called default variable Sreejith S Let’s Learn Perl
  • 134. Default scalar variable $ is called default variable It will be used if no other variable is specified foreach (a,b,c){ print uc ; } Sreejith S Let’s Learn Perl
  • 135. Accepting input Keyboard inputs can be accepted using STDIN Sreejith S Let’s Learn Perl
  • 136. Accepting input Keyboard inputs can be accepted using STDIN print "enter your name "; $name=<STDIN>; chomp $name; # chomp function is similar to fflush in C. # It removes trailing newline if any print "Welcome $namen"; Sreejith S Let’s Learn Perl
  • 137. Subroutines Subroutines can be defined using sub keyword Sreejith S Let’s Learn Perl
  • 138. Subroutines Subroutines can be defined using sub keyword ’@ ’ default array $v1=10;$v2=20; add($v1,$v2); sub add { ($a,$b)=@_; print $a+$b; } Sreejith S Let’s Learn Perl
  • 139. Scope of variables By default all variables are global Sreejith S Let’s Learn Perl
  • 140. Scope of variables By default all variables are global You can limit scope to a block/sub by using my. $v1=10; $v2=30; #v1,v2 global my $i = 10; Sreejith S Let’s Learn Perl
  • 141. File handling File handling can be done very easily Sreejith S Let’s Learn Perl
  • 142. File handling File handling can be done very easily To open a file in read mode Sreejith S Let’s Learn Perl
  • 143. File handling File handling can be done very easily To open a file in read mode open( $fh, < , data.txt); Sreejith S Let’s Learn Perl
  • 144. File handling File handling can be done very easily To open a file in read mode open( $fh, < , data.txt); File reading line by line can be done like Sreejith S Let’s Learn Perl
  • 145. File handling File handling can be done very easily To open a file in read mode open( $fh, < , data.txt); File reading line by line can be done like $line=<$fh>; Sreejith S Let’s Learn Perl
  • 146. File handling File handling can be done very easily To open a file in read mode open( $fh, < , data.txt); File reading line by line can be done like $line=<$fh>; File writing can be done using print and filehandle like this print $fh "hello"; Sreejith S Let’s Learn Perl
  • 147. File handling File handling can be done very easily To open a file in read mode open( $fh, < , data.txt); File reading line by line can be done like $line=<$fh>; File writing can be done using print and filehandle like this print $fh "hello"; Example Sreejith S Let’s Learn Perl
  • 148. File handling File handling can be done very easily To open a file in read mode open( $fh, < , data.txt); File reading line by line can be done like $line=<$fh>; File writing can be done using print and filehandle like this print $fh "hello"; Example open ( $fh, "<", "data.txt" ); #open file read only open ($fh1,">","udata.txt"); #Open file write mode while ( $line = <$fh>; ) { #read line by print "line=$line"; #display content on screen print $fh1 uc($line); #write upper cased content t } close($fh); close($fh1); Sreejith S Let’s Learn Perl
  • 149. Some Common String Functions There are many built in string functions Sreejith S Let’s Learn Perl
  • 150. Some Common String Functions There are many built in string functions Convert to upper case Sreejith S Let’s Learn Perl
  • 151. Some Common String Functions There are many built in string functions Convert to upper case $name = uc($name); Sreejith S Let’s Learn Perl
  • 152. Some Common String Functions There are many built in string functions Convert to upper case $name = uc($name); Convert only the first char to upper case Sreejith S Let’s Learn Perl
  • 153. Some Common String Functions There are many built in string functions Convert to upper case $name = uc($name); Convert only the first char to upper case $name = ucfirst($name); Sreejith S Let’s Learn Perl
  • 154. Some Common String Functions There are many built in string functions Convert to upper case $name = uc($name); Convert only the first char to upper case $name = ucfirst($name); Convert to lower case Sreejith S Let’s Learn Perl
  • 155. Some Common String Functions There are many built in string functions Convert to upper case $name = uc($name); Convert only the first char to upper case $name = ucfirst($name); Convert to lower case $name = lc($name); Sreejith S Let’s Learn Perl
  • 156. Some Common String Functions There are many built in string functions Convert to upper case $name = uc($name); Convert only the first char to upper case $name = ucfirst($name); Convert to lower case $name = lc($name); Convert only the first char to lower case Sreejith S Let’s Learn Perl
  • 157. Some Common String Functions There are many built in string functions Convert to upper case $name = uc($name); Convert only the first char to upper case $name = ucfirst($name); Convert to lower case $name = lc($name); Convert only the first char to lower case $name = lcfirst($name); Sreejith S Let’s Learn Perl
  • 158. Some Common String Functions There are many built in string functions Convert to upper case $name = uc($name); Convert only the first char to upper case $name = ucfirst($name); Convert to lower case $name = lc($name); Convert only the first char to lower case $name = lcfirst($name); Concatenation: ’.’ similar to strcat Sreejith S Let’s Learn Perl
  • 159. Some Common String Functions There are many built in string functions Convert to upper case $name = uc($name); Convert only the first char to upper case $name = ucfirst($name); Convert to lower case $name = lc($name); Convert only the first char to lower case $name = lcfirst($name); Concatenation: ’.’ similar to strcat $first_name = Larry; $last_name = Wall; $full_name = $first_name . . $last_name; Sreejith S Let’s Learn Perl
  • 160. Some Common Functions There are many built in functions Sreejith S Let’s Learn Perl
  • 161. Some Common Functions There are many built in functions Strings to Arrays : split Sreejith S Let’s Learn Perl
  • 162. Some Common Functions There are many built in functions Strings to Arrays : split @array = split( /;/, "Larry;Curly;Moe" ); @array= ("Larry", "Curly", "Moe"); Sreejith S Let’s Learn Perl
  • 163. Some Common Functions There are many built in functions Strings to Arrays : split @array = split( /;/, "Larry;Curly;Moe" ); @array= ("Larry", "Curly", "Moe"); Split into characters Sreejith S Let’s Learn Perl
  • 164. Some Common Functions There are many built in functions Strings to Arrays : split @array = split( /;/, "Larry;Curly;Moe" ); @array= ("Larry", "Curly", "Moe"); Split into characters @stooge = split( //, "curly" ); # array @stooge has 5 elements: c, u, r, l, y Sreejith S Let’s Learn Perl
  • 165. Some Common Functions There are many built in functions Strings to Arrays : split @array = split( /;/, "Larry;Curly;Moe" ); @array= ("Larry", "Curly", "Moe"); Split into characters @stooge = split( //, "curly" ); # array @stooge has 5 elements: c, u, r, l, y Join with any character you want Sreejith S Let’s Learn Perl
  • 166. Some Common Functions There are many built in functions Strings to Arrays : split @array = split( /;/, "Larry;Curly;Moe" ); @array= ("Larry", "Curly", "Moe"); Split into characters @stooge = split( //, "curly" ); # array @stooge has 5 elements: c, u, r, l, y Join with any character you want @array = 10, 20, 30, 40); $string = join(->, @array); # string = 10->20->30->40 Sreejith S Let’s Learn Perl
  • 167. Web Resource for Perl Web resources for Perl Sreejith S Let’s Learn Perl
  • 168. Web Resource for Perl Web resources for Perl www.perl.com www.perl.org www.perlmonks.org Sreejith S Let’s Learn Perl
  • 169. Recommended Reading Sreejith S Let’s Learn Perl
  • 170. Questions Sreejith S Let’s Learn Perl
  • 171. Thank You Sreejith S Let’s Learn Perl