Formats are the writing templates used in
Perl to output the reports. Perl has a mechanism which helps in generating simple reports and charts. Instead of executing, Formats are declared, so they may occur at any point in the program. Formats have their own namespace apart from the other types in Perl i.e. function named "tron" is not same as format named "tron". However, name of the filehandle in the program is the default name for the format associated with that filehandle.
Defining a Format
Syntax to define a Perl Format:
format FormatName = fieldline value_1, value_2, value_3 fieldline value_1, value_2, value_3 .
- Name of the format is denoted by the
FormatName. -
Fieldline is a particular way used to format the data. Fieldline can also hold text or
fieldholders. -
Value lines denotes/describes the values which will be entered into the
fieldlines. - Format is ended by a
single period (.) -
Fieldholders have the space for the data which will be entered later.
Syntax for Fieldholders: @<<<<<<< left-justified (with 7 field spaces by counting '@' and '<') @||||||| center-justified @###.#### numeric fieldholder @* multiline fieldholder
Using a Format
Write keyword is used to call on the format declaration.
Write FormatName;
Format name is the name of an open file handle and the write statement sends the output to the same file handle. In order to send the data to
STDOUT, format name needs to be associated with the STDOUT file handle.
Note: Use the
select() function for making sure that STDOUT is the selected file handle.
select (STDOUT);
In order to associate format name with STDOUT by setting the new format name with STDOUT, use the variables like
$~ or
$Format_Name $~ = "Format_Name";
Note: For writing report in any other file handle apart from the STDOUT, use the
select() function to select that file handle.
Example: Input: Using STDOUT. Perl #!/usr/bin/perl print "Content-type: text/html\n\n"; @First_Name = qw(Karthik Raman Shivam Tarun); @Last_Name = qw(Singh Biswas Anand Mishra); @ID = qw(101 186 009 359); @Phone_Number = qw(963x 885x 734x 921x); format DATA = @<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<< $First_Name[$k] $Last_Name[$k] $ID[$k] $Phone_Number[$k] . select(STDOUT); $~ = DATA; $k = 0; while ($k <= $#First_Name) { write; $k++; } 
Input: Using other file handle(Printing the output into a text file.) Perl #!/usr/bin/perl print "Content-type: text/html\n\n"; @First_Name = qw(Karthik Raman Shivam Tarun); @Last_Name = qw(Singh Biswas Anand Mishra); @ID = qw(101 186 009 359); @Phone_Number = qw(963x 885x 734x 921x); format DATA = @<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<<@<<<<<<<<<<<<<< $First_Name[$k] $Last_Name[$k] $ID[$k] $Phone_Number[$k] . open(FILE, ">file.txt"); select FILE; $~ = DATA; $k = 0; while ($k <= $#First_Name) { write; $k++; } close FILE; 
File where data is printed: 
Report Header and Footer
Header is something that appears at the top of each page. Instead of defining a template, just define a header and assign it to
$^ or
$FORMAT_NAME_TOP.
Footer has a fixed size. It can be achieved by checking for variable
$-. You can even print the footer by yourself if necessary using the syntax given below,
format FORMAT_NAME_BOTTOM End of Page $%
Example: Input: Using STDOUT Perl #!/usr/bin/perl print "Content-type: text/html\n\n"; format DATA_TOP = @|||||||||||||||||||||||||||||||||||||||||||||||||||| "Staff Members" ---------------------- First Last ID Phone ------------------------------------------------------ . @First_Name = qw(Karthik Raman Shivam Tarun); @Last_Name = qw(Singh Biswas Anand Mishra); @ID = qw(101 186 009 359); @Phone_Number = qw(963x 885x 734x 921x); format DATA = @<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<< $First_Name[$k] $Last_Name[$k] $ID[$k] $Phone_Number[$k] . select (STDOUT); $~ = DATA; $^ = DATA_TOP; $k = 0; while ($k <= $#First_Name) { write; $k++; } 
Input: Getting output into a text file. Perl #!/usr/bin/perl print "Content-type: text/html\n\n"; format DATA_TOP = @|||||||||||||||||||||||||||||||||||||||||||||||||||| "Staff Members" ---------------------- First Last ID Phone ------------------------------------------------------ . @First_Name = qw(Karthik Raman Shivam Tarun); @Last_Name = qw(Singh Biswas Anand Mishra); @ID = qw(101 186 009 359); @Phone_Number = qw(963x 885x 734x 921x); format DATA = @<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<<@<<<<<<<<<<<<<< $First_Name[$k] $Last_Name[$k] $ID[$k] $Phone_Number[$k] . open (FILE, ">file.txt"); select FILE; $~ = DATA; $^ = DATA_TOP; $k = 0; while ($k <= $#First_Name) { write; $k++; } close FILE; 
File where data is printed: 
Pagination
Pagination comes into the picture when you have a long report which will not fit in a single page. Use of variables like
$% or
$FORMAT_PAGE_NUMBER along with the header in the format helps in defining the page number to more than one page. Default number of lines in a page is 60 but it can be set manually too by using the variables
$= or
$FORMAT_LINES_PER_PAGE.
Example: Perl #!/usr/bin/perl print "Content-type: text/html\n\n"; format DATA_TOP = @>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> "[Page $%]" @|||||||||||||||||||||||||||||||||||||||||||||||||||| "Staff Members" ---------------------- First Last ID Phone ------------------------------------------------------ . @First_Name = qw(Karthik Raman Shivam Tarun); @Last_Name = qw(Singh Biswas Anand Mishra); @ID = qw(101 186 009 359); @Phone_Number = qw(963x 885x 734x 921x); format DATA = @<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<<@<<<<<<<<<<<<<<< $First_Name[$k] $Last_Name[$k] $ID[$k] $Phone_Number[$k] . select (STDOUT); $~ = DATA; $^ = DATA_TOP; $= = 1; $k = 0; while ($k <= $#First_Name) { write; $k++; } 
Similar Reads
Coercions in Perl In Perl, there are values of different types like strings, integers, rational numbers, and more. Coercion is responsible for converting one data type of data or object to another, behind the scenes where we magically just get what we want. It generally refers to "implicit type conversion" which is a
4 min read
Perl | Arrays In Perl, array is a special type of variable. The array is used to store the list of values and each object of the list is termed as an element. Elements can either be a number, string, or any type of scalar data including another variable. Example: @number = (50, 70, 46); @names = ("Geeks", "For",
6 min read
Perl | abs() function This function returns the absolute value of its argument. If a pure integer value is passed then it will return it as it is, but if a string is passed then it will return zero. If VALUE is omitted then it uses $_ Syntax: abs(VALUE) Parameter: VALUE: It is a required number which can be either positi
2 min read
Perl | y Operator The y operator in Perl translates all characters of SearchList into the corresponding characters of ReplacementList. Here the SearchList is the given input characters which are to be converted into the corresponding characters given in the ReplacementList. Syntax: y/SearchList/ReplacementList/ Retur
2 min read
Error Handling in Perl Error Handling in Perl is the process of taking appropriate action against a program that causes difficulty in execution because of some error in the code or the compiler. Processes are prone to errors. For example, if opening a file that does not exist raises an error, or accessing a variable that
5 min read