Damm algorithm: Difference between revisions

Revision as of 03:54, 10 January 2013

Revision as of 07:40, 13 January 2013

Line 108:

== Graphical illustration ==

[[File:Check digit TA quasigroup dhmd111rr illustration eg5724.svg]]

== Source code ==

=== C ===

<source lang="c">

char Taq(char* number)

{

const char taqDhmd111rr[]=

"0317598642""7092154863""4206871359""1750983426""6123045978"

"3674209581""5869720134""8945362017""9438617205""2581436790";

char interim='0';

char* p;

for(p=number;*p!='\0';++p){

if((unsigned char)(*p-'0')>9)

return '-'; //minus sign indicates an error: character is not a digit

interim=taqDhmd111rr[(*p-'0')+(interim-'0')*10];

}

return interim;

}

char CalculateCheckDigit(char* numberWithoutCheckDigit)

{

return Taq(numberWithoutCheckDigit);

}

typedef int BOOL;

BOOL IsCheckDigitValid(char* numberWithCheckDigit)

{

return Taq(numberWithCheckDigit)=='0';

}

</source>

== Strengths and weaknesses ==