Editing C preprocessor (section)

== Phases ==
Preprocessing is defined by the first four (of eight) ''phases of translation'' specified in the C Standard.

# Trigraph replacement: The preprocessor replaces [[C trigraph|trigraph sequences]] with the characters they represent. This phase was removed in [[C23 (C standard revision)|C23]] following the steps of [[C++17]].
# Line splicing: Physical source lines that are continued with [[escape character|escaped]] [[newline]] sequences are ''spliced'' to form logical lines.
# Tokenization: The preprocessor breaks the result into ''preprocessing tokens'' and [[Whitespace character|whitespace]]. It replaces comments with whitespace.
# Macro expansion and directive handling: Preprocessing directive lines, including file inclusion and conditional compilation, are executed. The preprocessor simultaneously expands macros and, since the 1999 version of the C standard, handles <code>_Pragma</code> operators.