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Running Bison to Make the Parser

Before running Bison to produce a parser, we need to decide how to arrange all the source code in one or more source files. For such a simple example, the easiest thing is to put everything in one file. The definitions of yylex, yyerror and main go at the end, in the "additional C code" section of the file (see The Overall Layout of a Bison Grammar).

For a large project, you would probably have several source files, and use make to arrange to recompile them.

With all the source in a single file, you use the following command to convert it into a parser file:

bison file_name.y

In this example the file was called rpcalc.y (for "Reverse Polish CALCulator"). Bison produces a file named file_name.tab.c, removing the .y from the original file name. The file output by Bison contains the source code for yyparse. The additional functions in the input file (yylex, yyerror and main) are copied verbatim to the output.