EAN 8 : How to calculate checksum digit?

Question

I need to create EAN 8 bar code programmatically. I search an algorithm to calculate the checksum digit.

Answer 1

int checkSum(const std::vector<int>& code) const
{
    if (code.size() < 8) return false;

    for( SIZE_T i = 0; i< code.size(); i++ )
    {
        if( code[i] < 0 ) return false;
    }

    int sum1 = code[1] + code[3] + code[5] 
    int sum2 = 3 * (code[0] + code[2] + code[4] + code[6]);

    int checksum_value = sum1 + sum2;
    int checksum_digit = 10 - (checksum_value % 10);
    if (checksum_digit == 10) checksum_digit = 0;

    return checksum_digit;
}

Answer 2

The algorithm is covered in this wikipedia article on EAN, note that EAN-8 is calculated in the same way as EAN-13.

Here's a worked example from http://www.barcodeisland.com/ean8.phtml :

Assuming we wish to encode the 7-digit message "5512345", we would calculate the checksum in the following manner:

Barcode          5     5     1     2     3     4     5
Odd/Even Pos?    O     E     O     E     O     E     O
Weighting        3     1     3     1     3     1     3
Calculation    5*3   5*1   1*3   2*1   3*3   4*1   5*3
Weighted Sum    15     5     3     2     9     4    15

The total is 15 + 5 + 3 + 2 + 9 + 4 + 15 = 53. 7 must be added to 53 to produce a number evenly divisible by 10, thus the checksum digit is 7 and the completed bar code value is "55123457".

string code="55123457";

int sum1 = code[1] + code[3] + code[5] 
int sum2 = 3 * (code[0] + code[2] + code[4] + code[6]);
int checksum_value = sum1 + sum2;

int checksum_digit = 10 - (checksum_value % 10);
if (checksum_digit == 10) 
    checksum_digit = 0;

Answer 3

Sorry for re-opening

JAVA VERSION

public int checkSum(String code){
        int val=0;
        for(int i=0;i<code.length();i++){
            val+=((int)Integer.parseInt(code.charAt(i)+""))*((i%2==0)?1:3);
        }

        int checksum_digit = 10 - (val % 10);
        if (checksum_digit == 10) checksum_digit = 0;

        return checksum_digit;
    }

Answer 4

Reawakened with a C# version:

    public static bool IsValidEan13(string eanBarcode)
    {
        return IsValidEan(eanBarcode, 13);
    }

    public static bool IsValidEan12(string eanBarcode)
    {
        return IsValidEan(eanBarcode, 12);
    }

    public static bool IsValidEan14(string eanBarcode)
    {
        return IsValidEan(eanBarcode, 14);
    }

    public static bool IsValidEan8(string eanBarcode)
    {
        return IsValidEan(eanBarcode, 8);
    }

    private static bool IsValidEan(string eanBarcode, int length)
    {
        if (eanBarcode.Length != length) return false;
        var allDigits = eanBarcode.Select(c => int.Parse(c.ToString(CultureInfo.InvariantCulture))).ToArray();
        var s = length%2 == 0 ? 3 : 1;
        var s2 = s == 3 ? 1 : 3;
        return allDigits.Last() == (10 - (allDigits.Take(length-1).Select((c, ci) => c*(ci%2 == 0 ? s : s2)).Sum()%10))%10;
    }

Answer 5

Here is a MySQL version for EAN13:

    SET @first12digits="123456789012";
    SELECT @first12digits,
IF (
    (@check:=10-MOD(
        (CAST(SUBSTRING(@first12digits, 1, 1) AS DECIMAL))+
        (CAST(SUBSTRING(@first12digits, 2, 1) AS DECIMAL) * 3)+
        (CAST(SUBSTRING(@first12digits, 3, 1) AS DECIMAL))+
        (CAST(SUBSTRING(@first12digits, 4, 1) AS DECIMAL) * 3)+
        (CAST(SUBSTRING(@first12digits, 5, 1) AS DECIMAL))+
        (CAST(SUBSTRING(@first12digits, 6, 1) AS DECIMAL) * 3)+
        (CAST(SUBSTRING(@first12digits, 7, 1) AS DECIMAL))+
        (CAST(SUBSTRING(@first12digits, 8, 1) AS DECIMAL) * 3)+
        (CAST(SUBSTRING(@first12digits, 9, 1) AS DECIMAL))+
        (CAST(SUBSTRING(@first12digits, 10, 1) AS DECIMAL) * 3)+
        (CAST(SUBSTRING(@first12digits, 11, 1) AS DECIMAL))+
        (CAST(SUBSTRING(@first12digits, 12, 1) AS DECIMAL) * 3)
    ,10)) = 10, 0, @check
    ) AS checkDigit;

There was a bug. If Calc result = 10 then check digit = 0.
Here below a better version for EAN14.

    SET @first13digits="1234567890123";
    SELECT @txCode13:=@first13digits,
        @iCheck := (
            10 - (
            (
                MID(@txCode13, 2, 1) +
                MID(@txCode13, 4, 1) +
                MID(@txCode13, 6, 1) +
                MID(@txCode13, 8, 1) +
                MID(@txCode13, 10, 1) +
                MID(@txCode13, 12, 1)
            ) + (
                MID(@txCode13, 1, 1) +
                MID(@txCode13, 3, 1) +
                MID(@txCode13, 5, 1) +
                MID(@txCode13, 7, 1) +
                MID(@txCode13, 9, 1) +
                MID(@txCode13, 11, 1) +
                MID(@txCode13, 13, 1)
                ) * 3 ) % 10
            ) AS iCheck,
        @iCheckDigit := IF(@iCheck = 10, 0, @iCheck) AS checkDigit,
        CONCAT(@t

xCode13, CAST(@iCheckDigit AS CHAR)) AS EAN14WithCheck

Answer 6

Here is the Java version for EAN13

 private int calcChecksum(String first12digits) {
    char[] char12digits = first12digits.toCharArray();
    int[] ean13 = {1,3};
    int sum = 0;
    for(int i = 0 ; i<char12digits.length; i++){
        sum += Character.getNumericValue(char12digits[i]) * ean13[i%2];
    }

    int checksum = 10 - sum%10;
    if(checksum == 10){
        checksum = 0;
    }

    return checksum;
}

Answer 7

class GTIN(object):

    def __init__(self, barcode=''):
        self.barcode = barcode

    def __checkDigit(self, digits):
            total = sum(digits) + sum(map(lambda d: d*2, digits[-1::-2]))
            return (10 - (total % 10)) % 10

    def validateCheckDigit(self, barcode=''):
        barcode = (barcode if barcode else self.barcode)
        if len(barcode) in (8,12,13,14) and barcode.isdigit():
            digits = map(int, barcode)
            checkDigit = self.__checkDigit( digits[0:-1] )
            return checkDigit == digits[-1]
        return False

    def addCheckDigit(self, barcode=''):
        barcode = (barcode if barcode else self.barcode)
        if len(barcode) in (7,11,12,13) and barcode.isdigit():
            digits = map(int, barcode)
            return barcode + str(self.__checkDigit(digits))
        return ''

Answer 8

Today I need a PHP version, I remember about this page and copy from the Java version. Thank you.

function getEAN13($txEan12)
    {
    $iVal=0;

    for($i=0; $i<strlen($txEan12); $i++)
        {
        $iSingleCharVal = intval(substr($txEan12, $i, 1));      // extract value of one char
        $iSingleCharMult = $iSingleCharVal * ($i%2==0 ? 1 : 3); // calculate depending from position
        $iVal+= $iSingleCharMult;   // sum
        }

    $iCheckDigit = 10 - ($iVal % 10);
    if ($iCheckDigit == 10) $iCheckDigit = 0;
    return $txEan12 . $iCheckDigit;
    }

Answer 9

Java Version:

It works perfectly

public static int checkSum(String code){
        int val=0;
        for(int i=0; i<code.length()-1; i++){
            val+=((int)Integer.parseInt(code.charAt(i)+""))*((i%2==0)?1:3);
        }

        int checksum_digit = (10 - (val % 10)) % 10;

        return checksum_digit;
    }

Answer 10

Python EAN13 check-digit calculation based on Najoua Mahi's Java function:

def generateEAN13CheckDigit(self, first12digits):
    charList = [char for char in first12digits]
    ean13 = [1,3]
    total = 0
    for order, char in enumerate(charList):
        total += int(char) * ean13[order % 2]

    checkDigit = 10 - total % 10
    if (checkDigit == 10):
        return 0
    return checkDigit

Answer 11

This works on both EAN 13 and EAN8:

public static String generateEAN(String barcode) {
    int first = 0;
    int second = 0;

    if(barcode.length() == 7 || barcode.length() == 12) {

        for (int counter = 0; counter < barcode.length() - 1; counter++) {
            first = (first + Integer.valueOf(barcode.substring(counter, counter + 1)));
            counter++;
            second = (second + Integer.valueOf(barcode.substring(counter, counter + 1)));
        }
        second = second * 3;
        int total = second + first;
        int roundedNum = Math.round((total + 9) / 10 * 10);

        barcode = barcode + String.valueOf(roundedNum - total);
    }
    return barcode;
}

Answer 12

This is a code I wrote in VFP (Visual FoxPro 9), for both EAN-8 and EAN-13

Lparameters lcBarcode,llShowErrorMessage

If Vartype(m.lcBarcode)<>'C'
    If m.llShowErrorMessage
        MessageBox([Type of parameter is incorect!],0+16,[Error Message])
    EndIf 
    Return .f.
EndIf 

If Len(Chrtran(Alltrim(m.lcBarcode),[0123456789],[]))>0
    If m.llShowErrorMessage
        MessageBox([Provided barcode contains invalid characters!],0+16,[Error Message])
    EndIf 
    Return .f.
EndIf 

If Len(Alltrim(m.lcBarcode))=0
    If m.llShowErrorMessage
        MessageBox([The length of provided barcode is 0 (zero)!],0+16,[Error Message])
    EndIf 
    Return .f.
EndIf 

If !InList(Len(Alltrim(m.lcBarcode)),8,13)
    If m.llShowErrorMessage
        MessageBox([Provided barcode is not an EAN-8 or EAN-13 barcode!],0+16,[Error Message])
    EndIf 
    Return .f.
EndIf 

Local lnCheck as Integer, lnSum as Integer, lnOriginalCheck as Integer,jj as Integer

jj=0
lnSum=0
m.lnOriginalCheck = Cast(Right(Alltrim(m.lcBarcode),1) as Integer)
m.lcBarcode = Left(Alltrim(m.lcBarcode),Len(Alltrim(m.lcBarcode))-1) 

For ii = Len(m.lcBarcode) to 1 step -1
    jj=jj+1
    lnSum = lnSum + Cast(Substr(m.lcBarcode,ii,1) as Integer) * Iif(Mod(jj,2)=0,1,3)
Next 
lnCheck = 10-Mod(lnSum,10)
lnCheck = Iif(lnCheck =10,0,lnCheck)

Return (lnCheck = lnOriginalCheck)

Answer 13

JavaScript version for EAN-8 and EAN-13

function checksum(code) {
    const sum = code.split('').reverse().reduce((sum, char, idx) => {
        let digit = Number.parseInt(char);
        let weight = (idx + 1) % 2 === 0 ? 1 : 3;
        let partial = digit * weight;
        return sum + partial;
    }, 0);

    const remainder = sum % 10;
    const checksum = remainder ? (10 - remainder) : 0;

    return checksum;
}