Programming Perl, 3rd Edition

Chapter 29. Functions

This chapter describes the built-in Perl functions in alphabetical order^[1] for convenient reference. Each function description begins with a brief summary of the syntax for that function. Parameter names like THIS represent placeholders for actual expressions, and the text following the syntax summary will describe the semantics of supplying (or omitting) the actual arguments.

You can think of functions as terms in an expression, along with literals and variables. Or you can think of them as prefix operators that process the arguments after them. We call them operators half the time anyway.

Some of these operators, er, functions take a LIST as an argument. Elements of the LIST should be separated by commas (or by =>, which is just a funny kind of comma). The elements of the LIST are evaluated in a list context, so each element will return either a scalar or a list value, depending on its sensitivity to list context. Each returned value, whether scalar or list, will be interpolated as part of the overall sequence of scalar values. That is, all the lists get flattened into one list. From the viewpoint of the function receiving the arguments, the overall argument LIST is always a single-dimensional list value. (To interpolate an array as a single element, you must explicitly create and interpolate a reference to the array instead.)

Predefined Perl functions may be used either with or without parentheses around their arguments; the syntax summaries in this ...