A.3 M4 Dependency

The macro processor m4(7) must be installed wherever flex is installed. flex invokes `m4', found by searching the directories in the PATH environment variable. Any code you place in section 1 or in the actions will be sent through m4. Please follow these rules to protect your code from unwanted m4 processing.

• Do not use symbols that begin with, `m4_', such as, `m4_define', or `m4_include', since those are reserved for m4 macro names. If for some reason you need m4_ as a prefix, use a preprocessor #define to get your symbol past m4 unmangled.
• Do not use the strings `[[' or `]]' anywhere in your code. The former is not valid in C, except within comments and strings, but the latter is valid in code such as x[y[z]]. The solution is simple. To get the literal string "]]", use "]""]". To get the array notation x[y[z]], use x[y[z] ].

m4 is only required at the time you run flex. The generated scanner is ordinary C or C++, and does not require m4.

This document was generated by Wolfram Kahl on September, 9 2006 using texi2html 1.76.