Contents of The ifthen Style Option

The `ifthen` Style Option

This option provides two programming language features that are useful only for people who already know how to program. It defines the two commands

\ifthenelse{test}{then clause}{else clause}
\whiledo{test}{do clause}
that implement the following two Pascal language structures

if test then then clause else else clause while test do do clause
The then, else, and do clauses are ordinary L^ATEX input; test is one of the following:

A relation between two numbers formed with <, >, or =; for example, \value{page}>3.
\equal{string1}{string2}, which evaluates to true if string1 and string2 are the same strings of characters after all commands have been replaced by their definitions. (Upper- and lowercase letters are unequal.)
A logical combination of the above two kinds of tests using the operators \or, \and, and \not and the parentheses \( and \)—for example:
```
\not \( \value{section} = 1  \and  \equal{Jones}{\myname} \)
```

The test argument is a violently moving argument, which means that not only fragile commands but even some commands that are not normally fragile will break, causing TEX to enter an infinite loop. The \protect command works in these situations.

These commands, together with \renewcommand and the commands of Section C.7.4 for manipulating counters, open up a whole new world of hacking.