4.9 Conditionals and loops

There are three different builtin conditionals in T4.

The first is \ifelse. It takes four arguments:

\ifelse{string-1}{string-2}{then}{else}

If string-1 and string-2 are equal (character for character), it expands to then, otherwise it expands to else.

The second is \ifelsex.

\ifelsex{string-1}{string-2}{then}{else}

Unlike \ifelse is not to expand string-1 even when it is a macro, \ifelsex first expands string-1, and then tests with string-2.

The third is \ifdef.

\ifdef{macro-name}{then}{else}

It checks whether there is a macro named macro-name, if so, it expands to then, otherwise it expands to else.