3.1 Input Format to gperf

You can control the input file format by varying certain command-line arguments, in particular the ‘-t’ option. The input's appearance is similar to GNU utilities flex and bison (or UNIX utilities lex and yacc). Here's an outline of the general format:

declarations
%%
keywords
%%
functions

Unlike flex or bison, the declarations section and the functions section are optional. The following sections describe the input format for each section.

It is possible to omit the declaration section entirely, if the ‘-t’ option is not given. In this case the input file begins directly with the first keyword line, e.g.:

january
february
march
april
...