Chapter 5. Function Reference
This chapter gives a brief description of Perl’s built-in functions. Each description gives the syntax of the function, with the types and order of its arguments .
Required arguments are shown in italics, separated by commas. If
an argument must be a specific variable type, that variable’s identifier
will be used (e.g., a percent sign for a hash, % hash). Optional
arguments are placed in brackets. Do not use the brackets in function
calls unless you really want to use an anonymous hash reference.
There are different ways to use a built-in function. For starters, any argument that requires a scalar value can be made up of any expression that returns one. For example, you can obtain the square root of the first value in an array:
$root = sqrt (shift @numbers);
shift removes the first element
of @numbers and returns it to be used
by sqrt.
Many functions take a list of scalars for arguments. Any array variable or other expression that returns a list can be used for all or part of the arguments. For example:
chmod (split /,/ FILELIST>); # An expression returns a list chmod 0755, @executables; # Array used for part of arguments
In the first line, the split
expression reads a string from a filehandle and splits it into a list.
The list provides proper arguments for chmod. The second line uses an array that
contains a list of filenames for chmod to act upon.
Parentheses are not required around a function’s arguments. However, without parentheses, functions are viewed ...