# Text.StrCheckSum Method

Version:Available or changed with runtime version 1.0.

Calculates a checksum for a string that contains a number. If the source is empty, 0 is returned. Each char in the source and in the weight must be a numeric character 0-9, otherwise an exception is thrown. If the WeightString parameter is shorter then the source, it is padded with '1' up until the length of source. If the WeightString parameter is longer than the source, an exception is thrown.

## Syntax

```
CheckNumber := Text.StrCheckSum(String: String [, WeightString: String] [, Modulus: Integer])
```

Note

This method can be invoked without specifying the data type name.

## Parameters

*String*

Type: String

This string contains the number for which you want to calculate a checksum. You can only enter the numeric characters 0-9 in this string. If you enter anything else, a run-time error will occur. If String is empty, 0 is returned.

*[Optional] WeightString*

Type: String

This string contains numbers that you want to use as weights when calculating the checksum. The default value is a string that contains STRLEN(String) '1'-characters.

*[Optional] Modulus*

Type: Integer

The number that you want to use in the checksum formula. The default value is 10.

## Return Value

*CheckNumber*

Type: Integer

The resulting checksum value.

## Example 1

This example shows how to use the StrCheckSum method to calculate a checksum.

```
var
StrNumber: Text[30];
Weight: Text[30];
Modulus: Integer;
Text000: Label 'The number: %1\\';
Text001: Label 'has the checksum: %2';
begin
StrNumber := '4378';
Weight := '1234';
Modulus := 7;
CheckSum := StrCheckSum(StrNumber, Weight, Modulus);
Message(Text000 + Text001, StrNumber, CheckSum);
end;
```

The formula is:

(7 - (4x1 + 3x2 + 7x3 + 8x4) MOD 7) MOD 7=0

The message window displays the following:

**The number: 4378**

**has the checksum: 0**

## Example 2

This example shows how to use the StrCheckSum method to calculate a modulus 10 checksum for a bar code.

The StrCheckSum method can be used to calculate checksums for 13- and 8-digit European Article Number (EAN) and EAN-compatible bar codes such as a Universal Product Code (UPC) or Japanese Article Number (JAN).

A 13-digit EAN code has the following format:

The 12 digits in positions 13 to 2 are used to calculate the checksum at position 1.

Starting with position 2, all even values are totaled. The result is then multiplied by three. This value is called Even.

Starting with position 3, all odd values are totaled. The result is called Odd.

Total=Even + Odd.

The modulus 10 checksum is then (10 - Total MOD 10) MOD 10.

```
var
StrNumber: Text[30];
Weight: Text[30];
Modulus: Integer;
Text000: Label 'The EAN code: %1\\';
Text001: Label 'has the checksum: %2';
begin
StrNumber := '577622135746';
Weight := '131313131313';
CheckSum := StrCheckSum(StrNumber, Weight);
Message(Text000 + Text001, StrNumber, CheckSum);
end;
```

The message window displays the following:

**The EAN code: 577622135746**

**has the checksum: 3**

## See Also

Text Data Type

Getting Started with AL

Developing Extensions