www.delorie.com/gnu/docs/gforth/gforth_17.html   search  
 
Buy GNU books!


Gforth Manual

[ < ] [ > ]   [ << ] [ Up ] [ >> ]         [Top] [Contents] [Index] [ ? ]

3.5 Arithmetics

The words +, -, *, /, and mod always operate on the top two stack items:

 
2 2 .s
+ .s
.
2 1 - .
7 3 mod .

The operands of -, /, and mod are in the same order as in the corresponding infix expression (this is generally the case in Forth).

Parentheses are superfluous (and not available), because the order of the words unambiguously determines the order of evaluation and the operands:

 
3 4 + 5 * .
3 4 5 * + .

Assignment:
What are the infix expressions corresponding to the Forth code above? Write 6-7*8+9 in Forth notation(3).

To change the sign, use negate:

 
2 negate .

Assignment:
Convert -(-3)*4-5 to Forth.

/mod performs both / and mod.

 
7 3 /mod . .

Reference: 5.5 Arithmetic.


  webmaster     delorie software   privacy  
  Copyright 2003   by The Free Software Foundation     Updated Jun 2003