Page:4SIGHT manual- a computer program for modelling degradation of underground low level waste concrete vaults (IA 4sightmanualcomp5612snyd).pdf/67

 Appendix A

A Input Parsing

The input parsing was accomplished using public domain versions of LEX and YACC written for the PC. These tools simplify parsing user input, facilitating modification and extensions in program capabilities. The user unfamiliar with LEX and YACC should read the book by Mason and Brown listed in the references. To obtain a copy of the public domain version, access the following directory through anonymous ftp:

machine: omnigate.clarkson.edu

directory: pub/msdos/djgpp

LEX and YACC are programs that take as input user specifications for a particular syntax and create a C file which performs the functions specified in the user LEX and YACC files. The resulting C file is then simply #include-ed into the main C program. Of course, the user can code the parsing directly in C, but LEX and YACC make the coding less errorsome and more extensible.