Damm algorithm: Difference between revisions

=={{header|Action!}}==

<lang Action!>BYTE FUNC Damm(CHAR ARRAY a)

BYTE ARRAY table=[

0 3 1 7 5 9 8 6 4 2

7 0 9 2 1 5 4 8 6 3

4 2 0 6 8 7 1 3 5 9

1 7 5 0 9 8 3 4 2 6

6 1 2 3 0 4 5 9 7 8

3 6 7 4 2 0 9 5 8 1

5 8 6 9 7 2 0 1 3 4

8 9 4 5 3 6 2 0 1 7

9 4 3 8 6 1 7 2 0 5

2 5 8 1 4 3 6 7 9 0]

BYTE i,x,c

x=0

FOR i=1 TO a(0)

DO

c=a(i)

IF c<'0 OR c>'9 THEN

RETURN (0)

FI

c==-'0

x=table(x*10+c)

OD

IF x=0 THEN

RETURN (1)

FI

RETURN (0)

PROC Test(CHAR ARRAY a)

BYTE i

Print(a) Print(" -> ")

IF Damm(a)=1 THEN

PrintE("valid")

ELSE

PrintE("invalid")

FI

RETURN

PROC Main()

Test("5724")

Test("5727")

Test("112946")

Test("112949")

RETURN</lang>

{{out}}

[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Damm_algorithm.png Screenshot from Atari 8-bit computer]

<pre>

5724 -> valid

5727 -> invalid

112946 -> valid

112949 -> invalid

</pre>