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In some cases directives specify global behavior, while in other cases they only affect a local section, such as a block of programming code. In some cases, such as some C programs, directives are optional compiler hints and may be ignored, but normally they are prescriptive and must be followed. However, a directive does not perform any action ...
In computer programming, indentation style is a convention, a.k.a. style, governing the indentation of blocks of source code.An indentation style generally involves consistent width of whitespace (indentation size) before each line of a block, so that the lines of code appear to be related, and dictates whether to use space or tab characters for the indentation whitespace.
The rules a compiler applies to the source creates implicit standards. For example, Python code is much more consistently indented than, say Perl, because whitespace (indentation) is actually significant to the interpreter. Python does not use the brace syntax Perl uses to delimit functions. Changes in indentation serve as the delimiters.
Syntax highlighting and indent style are often used to aid programmers in recognizing elements of source code. This Python code uses color-coded highlighting. In computer science, the syntax of a computer language is the rules that define the combinations of symbols that are considered to be correctly structured statements or expressions in ...
Technically, Perl does not have a convention for including block comments in source code, but POD is routinely used as a workaround. PHP. PHP supports standard C/C++ style comments, but supports Perl style as well. Python. The use of the triple-quotes to comment-out lines of source, does not actually form a comment. [19]
For example, Python's PEP 8 is a widely recognized style guide that outlines best practices for writing Python code. In contrast, languages like C or Java may have industry standards that are either formally documented or adhered to by convention.
Many programming languages support conditional compilation. Typically compiler directives define or "undefine" certain variables; other directives test these variables and modify compilation accordingly. For example, not using an actual language, the compiler may be set to define "Macintosh" and undefine "PC", and the code may contain:
This directive executes a program, script, or shell command on the server. The cmd parameter specifies a server-side command; the cgi parameter specifies the path to a CGI script. The PATH_INFO and QUERY_STRING of the current SSI script will be passed to the CGI script, as a result "exec cgi" should be used instead of "include virtual".