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Note that the C code under the CODE: section calls the _do_sv_catsv() pure-C function that was defined in the prior section. Perl’s documentation explains the meaning and purpose of all of the “special” symbols (e.g., aTHX_ and RETVAL) shown above. To make this module available to Perl it must be compiled.
For example, the following Perl one-liner will reverse all the bytes in a file: perl -0777e 'print scalar reverse <>' filename While most Perl one-liners are imperative, Perl's support for anonymous functions, closures, map, filter (grep) and fold (List::Util::reduce) allows the creation of 'functional' one-liners.
There are many ways to write object-oriented code in Perl. The most basic is using "blessed" references. This works by identifying a reference of any type as belonging to a given package, and the package provides the methods for the blessed reference. For example, a two-dimensional point could be defined this way:
Once Perl code is compiled, there is additional overhead during the execution phase that typically isn't present for programs written in compiled languages such as C or C++. Examples of such overhead include bytecode interpretation, reference-counting memory management, and dynamic type-checking. [124]
In C, the functions strcmp and memcmp perform a three-way comparison between strings and memory buffers, ... Here is a composition example in Perl. ... Code of Conduct;
Perl Compatible Regular Expressions (PCRE) is a library written in C, which implements a regular expression engine, inspired by the capabilities of the Perl programming language. Philip Hazel started writing PCRE in summer 1997. [ 3 ]
All looping constructs except for the C-style for-loop can have a continue block that is executed after each iteration of the loop body, before the loop condition is evaluated again. label for ( expr1 ; expr2 ; expr3) block. This is the so-called C-style for loop. The first expression is evaluated prior to the first loop iteration.
What follows are examples of "Hello, World" implemented in different styles of modules. It must be understood that a module is not necessary in Perl; functions and code can be defined and used anywhere. This is just for example purposes. Contrast with Java where a class is always necessary. A real "Hello, World" function would be written like so: