International Bank Account Number

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The International Bank Account Number (IBAN) is an international standard for numbering bank accounts. It is ISO 13616 standard. The IBAN consists of up to 34 alphanumeric characters, comprising a country code, two check digits and a detailed bank account-number.

The country code using ISO 3166-1 alpha-2. The check digits are calculated according to ISO 7064 (MOD97-10) using StrMOD97

Function IsValidIBAN

Function IsValidIBAN() checks if an IBAN is valid.

function IsValidIBAN( s: string ): boolean;

  function ReplaceLetterWithNumbers( ch: char ):string;
  var
    i: integer;
  begin
    i := ord( upcase( ch ) ) - ord( 'A' ) + 10;
    result := IntToStr( i );
  end;   

var
  a_char: char;
  s1: string;
  i: integer;
begin
  s := DelSpace( s );
  s1 := copy( s, 1, 4);
  delete( s, 1, 4 );
  a_char := s1[1];
  delete( s1, 1, 1 );
  s := s + ReplaceLetterWithNumbers( a_char );
  a_char := s1[1];
  delete( s1, 1, 1 );
  s := s + ReplaceLetterWithNumbers( a_char );
  s := s + s1;
  i := StrMOD97( s );
  result := (i = 1);
end;