In source files, we can include Preprocessor directives.
Line-matching Preprocessor command.
These directives tells the Preprocessor to perform specific actions.
However, the Preprocessor is sometimes useful on its own.
And why not skip it and make the Preprocessor faster?”?
Effectively, it is left alone by the Preprocessor whenever it's used in running text.
This is not an error to the Preprocessor(but many macros will then expand to invalid code).
Later, many modifications were made to it,
and Today we know it as PHP or Hypertext Preprocessor.
If you request textual output from the Preprocessor with the-E option, it will be in UTF-8.
The developer must have enough time to learn new features present in this Preprocessor before using it.
This helps the Preprocessor report correct column numbers in warnings or errors,
even if tabs appear on the line.
The Preprocessor also warns if the macro has not
been used at the time it is redefined or undefined.
If no-MF switch is given the Preprocessor sends the rules to the same place it would
have sent preprocessed output.
U Like D except that only macros that are expanded,
or whose definedness is tested in Preprocessor directives, are output;
I have been a long time fan of their CSSHat plugin,
which generates CSS or Preprocessor code from Photoshop layers.
These are' ident'(always),' pragma'(only if the Preprocessor does not handle the pragma itself),
and' define' and' undef'(with certain debugging options).
The Preprocessor will also warn if the macro has
not been used at the time it is redefined or undefined.
PHP(Hypertext Preprocessor) is one of the most pupolar web programming language
and has been used by million of today's website.
The Preprocessor still recognizes and removes comments,
so that you can pass a file preprocessed with'-C' to the compiler without problems.
Note: If a macro is actually used, but
only used in skipped conditional blocks, then the Preprocessor reports it as unused.
For the angle-bracket form include < file> , the Preprocessor's default behavior is to look only
in the standard system directories.
The PHP reference implementation is now produced by The PHP Group and is now stands for the recursive acronym PHP:
Hypertext Preprocessor.
Preprocessor conditionals can test arithmetic expressions, or
whether a name is defined as a macro, or both simultaneously using the special defined operator.
When this option is enabled, the Preprocessor will emit, after the
initial linemarker, a second linemarker with the current working directory followed by two slashes.
So for most intents and purposes a translation unit is a single C++ source file and the header or
other files it includes via the Preprocessor include mechanism.
Hypertext Preprocessor, popularly known as PHP is a revolutionary
programming language designed for developing various website applications such as web resources, web APIs and most importantly web services.
Pragma once' does not have the problems that‘ import' does,
but it is not recognized by all Preprocessors, so you cannot rely on it in a portable program.
This might be useful when running the Preprocessor on something that is not C code,
and will be sent to a program which might be confused by the linemarkers.
The C language, which also uses the Preprocessor, does not have as many header files as the C++ language,
but in C++ you can use all the C header files.
Previous GNU Preprocessor implementations and documentation were incorrect on this point,
insisting that a function-like macro that takes a single argument be passed a space if an empty argument was required.