1.Introduction

compiling principle exercise

this exercise is using flex and yacc to develop a calculator.flex is a lexical analyzer,and yacc is a parser.

this project contains cal.l and cal.y. cal.l describe lexical rules and cal.y describe grammar rules.

and now it distinguishs integer from floating point.

2.Dependencies

bison

flex

sudo apt-get install flex

sudo apt-get install bison

3.How to Use

3.1 Compile

flex cal.l

bison -d cal.y

gcc -o cal cal.tab.c lex.yy.c -ly -lm -lfl

3.2 Run

./cal

4.Current Support Operator

+

-

*

/

%

!

^

sin

cos

tan

log

exp

5.Result