Caculator

Use lex & bison to implement a simple calculator.

Dependencies

• lex: lexical analyzer, "scanner" or "lexer"
• bison: parser generator

Ubuntu Installation

• Install flex and bison

sudo apt-get install flex bison

• Make it in the current directory

make
./calculator

• (optional) Install it in /home/bin

sudo make install
caculator

• Uninstall it

sudo make uninstall

Functions

• basic arithmetic: addition, subtraction, multiplication, division, MINUS, ABS.
• Custom variables.
• Common mathematical functions: sqrt, exp, log, sin, cos.
• Function for console printing: print.
• Branch statement: if-then-else, while-do.
• User-defined functions.

TODO

• Storage for last result.
• Make user-defined functions more robust (such as add return).
• Add error recovery.
• Memory to user-defined functions.
• Not limited in float number caculation (Casio fraction).

Sample Usage

> 1.4 + 2*(2+3);
= 11.4
> sin(3.141592653/2);
=    1
> ac=log(1024);
= 6.931
> if (ac>0) then {ac=-1;} else {ac=1; ac=2*ac;} 
=   -1
> b=sqrt(100);
=   10
> while (b>0) do {b=b-1; print(b);}
=    9
=    8
=    7
=    6
=    5
=    4
=    3
=    2
=    1
=    0
=    0
> def myfunc(a,b,c) {(a+b+c)/3;}
Function Defined myfunc
> myfunc(1,2,3);
=    2
> myfunc(1,2);
error: too few args in call to myfunc
=    0
> |-1|;
=    1
> do=-1;
error: syntax error
> 

Directory

• calculator.l: flex file
• calculator.y: bison file
• funcs.c & funcs.h: AST kernel
• Makefile: make | make clean | make install | make uninstall