[<< wikibooks] TeX/if
== Synopsis ==
\if   [\else ] \fi


== Description ==
The \if command denotes the start of an if-then-else control structure.  The forms  and  must expand to tokens.  and  can be either a character or a control sequence. If  and  both expand to the same character code then  is processed; otherwise it is ignored. If the \else section is included and  and  expand to different character codes, then  is processed; otherwise it is ignored.


== A small LaTeX example ==
Here is a small LaTeX example, demonstrating the use of \if.

This example generates the output: 

undefed
defed, 1
defed