Dynamics 365 Business Central: How to reverse a string in AL

Hi, Readers.
Today I would like to share another mini tip about Business Central, how to reverse a string in AL. For example, the user want to reverse the name of the customer, Adatum Corporation -> noitaroproC mutadA.

In this blog, I’ve summarized three easy ways to do this, and you can choose the one you prefer.

1. Using List Data Type

There is a very convenient method in List Data Type.
List.Reverse() Method: Reverses the order of the elements in the entire List.
For example,

PS: Business Central 2023 wave 1 (BC22): Iterating with foreach on Text variables

Source code: Github

pageextension 50125 CustomerListExt extends "Customer List"
{
    actions
    {
        addafter(Email)
        {
            action(ReverseSelectedCustomerName)
            {
                Caption = 'Reverse Customer Name';
                Image = ReverseRegister;
                ApplicationArea = All;
                Promoted = true;
                PromotedCategory = Process;
                PromotedIsBig = true;

                trigger OnAction()
                var
                    StringList: List of [Text];
                    StringLetter: Text;
                    ReversedString: Text;
                begin
                    ReversedString := '';
                    foreach StringLetter in Rec.Name do
                        StringList.Add(StringLetter);
                    StringList.Reverse();
                    foreach StringLetter in StringList do
                        ReversedString += StringLetter;
                    Message(ReversedString);
                end;
            }
        }
    }
}

2. Using indexing with []

We can used the method below, [] to convert the string into a single-dimensional array. What was obtained was a number (Character Code).

Rec.Name[i]

More details: How to extract characters from a string (indexing with []).
For exmaple,

Source code: Github

pageextension 50125 CustomerListExt extends "Customer List"
{
    actions
    {
        addafter(Email)
        {
            action(ReverseSelectedCustomerName)
            {
                Caption = 'Reverse Customer Name';
                Image = ReverseRegister;
                ApplicationArea = All;
                Promoted = true;
                PromotedCategory = Process;
                PromotedIsBig = true;

                trigger OnAction()
                var
                    ReversedString: Text;
                    i: Integer;
                    j: Integer;
                begin
                    j := 0;
                    for i := StrLen(Rec.Name) downto 1 do begin
                        j += 1;
                        ReversedString[j] := Rec.Name[i];
                    end;
                    Message(ReversedString);
                end;
            }
        }
    }
}

PS: Dynamics 365 Business Central: How to prohibit users from entering illegal characters such as emoji, Hiragana, kanji, etc.

3. Using Text.CopyStr(Text, Integer [, Integer]) Method

Source code: Github

pageextension 50125 CustomerListExt extends "Customer List"
{
    actions
    {
        addafter(Email)
        {
            action(ReverseSelectedCustomerName)
            {
                Caption = 'Reverse Customer Name';
                Image = ReverseRegister;
                ApplicationArea = All;
                Promoted = true;
                PromotedCategory = Process;
                PromotedIsBig = true;
                trigger OnAction()
                var
                    ReversedString: Text;
                    i: Integer;
                begin
                    for i := StrLen(Rec.Name) downto 1 do
                        ReversedString += CopyStr(Rec.Name, i, 1);
                    Message(ReversedString);
                end;
            }
        }
    }
}

Very simple, give it a try!!!😁

END

Hope this will help.

Thanks for reading.

ZHU