Numeric comparison (Gforth Manual)

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6.5.7 Numeric comparison ¶

All these comparison words produce -1 (all bits set) if the condition is true, otherwise 0. Note that the words that compare for equality (= <> 0= 0<> d= d<> d0= d0<>) work for for both signed and unsigned numbers.

< ( n1 n2 – f ) core “less-than”

<= ( n1 n2 – f ) gforth-0.2 “less-or-equal”

<> ( n1 n2 – f ) core-ext “not-equals”

= ( n1 n2 – f ) core “equals”

> ( n1 n2 – f ) core “greater-than”

>= ( n1 n2 – f ) gforth-0.2 “greater-or-equal”

0< ( n – f ) core “zero-less-than”

0<= ( n – f ) gforth-0.2 “zero-less-or-equal”

0<> ( n – f ) core-ext “zero-not-equals”

0= ( n – f ) core “zero-equals”

0> ( n – f ) core-ext “zero-greater-than”

0>= ( n – f ) gforth-0.2 “zero-greater-or-equal”

u< ( u1 u2 – f ) core “u-less-than”

u<= ( u1 u2 – f ) gforth-0.2 “u-less-or-equal”

u> ( u1 u2 – f ) core-ext “u-greater-than”

u>= ( u1 u2 – f ) gforth-0.2 “u-greater-or-equal”

within ( u1 u2 u3 – f ) core-ext “within”

u2<u3 and u1 in [u2,u3) or: u2>=u3 and u1 not in [u3,u2). This works for unsigned and signed numbers (but not a mixture). Another way to think about this word is to consider the numbers as a circle (wrapping around from max-u to 0 for unsigned, and from max-n to min-n for signed numbers); now consider the range from u2 towards increasing numbers up to and excluding u3 (giving an empty range if u2=u3); if u1 is in this range, within returns true.

d< ( d1 d2 – f ) double “d-less-than”

d<= ( d1 d2 – f ) gforth-0.2 “d-less-or-equal”

d<> ( d1 d2 – f ) gforth-0.2 “d-not-equals”

d= ( d1 d2 – f ) double “d-equals”

d> ( d1 d2 – f ) gforth-0.2 “d-greater-than”

d>= ( d1 d2 – f ) gforth-0.2 “d-greater-or-equal”

d0< ( d – f ) double “d-zero-less-than”

d0<= ( d – f ) gforth-0.2 “d-zero-less-or-equal”

d0<> ( d – f ) gforth-0.2 “d-zero-not-equals”

d0= ( d – f ) double “d-zero-equals”

d0> ( d – f ) gforth-0.2 “d-zero-greater-than”

d0>= ( d – f ) gforth-0.2 “d-zero-greater-or-equal”

du< ( ud1 ud2 – f ) double-ext “d-u-less-than”

du<= ( ud1 ud2 – f ) gforth-0.2 “d-u-less-or-equal”

du> ( ud1 ud2 – f ) gforth-0.2 “d-u-greater-than”

du>= ( ud1 ud2 – f ) gforth-0.2 “d-u-greater-or-equal”