SAS code for verifying the check digit/*******************************************
PNR_CHK.SAS
This code reads 10-digit person numbers and
checks that the check digit (the 10th digit
in the PNR) is correct.
It is assumed that PNR is a character
variable of length 10.
*******************************************/
/*******************
Read some test data
********************/
data temp;
input pnr $ 1-10;
cards;
3103170993
3103170999
6812241450
6812241457
6511280693
6511280692
;
run;
data pnr_chk;
set temp;
length product $ 18 result $ 3;
array two_one {9} (2 1 2 1 2 1 2 1 2);
/*********************************************
multiply each of the first 9 digits in PNR by
the corresponding digit in the array two_one
and concatenate the result.
The COMPRESS function removes blanks.
*********************************************/
do i = 1 to 9;
product=compress(product||(substr(pnr,i,1)
*two_one{i}));
end;
/** Now we sum the digits **/
do i = 1 to length(product);
sum=sum(sum,substr(product,i,1));
end;
/** extract the check digit from PNR **/
chk=substr(pnr,10,1);
/** calculate the correct check digit **/
corr_chk=mod(10-mod(sum,10),10);
if chk=corr_chk then result='ok';
else result='bad';
label
chk='Actual check number'
corr_chk='Correct check number'
pnr='Personnummer (10 digits)'
;
run;
proc print data="pnr_chk;"
var pnr chk product sum corr_chk result;
run;
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