Cross Ref > Operators

Java uses = for it's assignment operator.

Delphi uses := for it's assignment operator.

var

  FullName: String;

  Age: Integer;

begin

  FullName := "Randy Spitz";
  Age := 38;

end

The Java comparison operators are:

Common comparison operators:

//Does Delphi evaluate the math correctly? Yes!

//Refer to math.pas MaxSingle for more info.

if (0.1 + 0.1 + 0.1 = 0.3) then
  ShowMessage('correct')
else
  ShowMessage('not correct')

 Delphi Comparison Operators (=, <>)

Length() or SizeOf() will correctly identify an unassigned string variable or an empty string.

if length(s) = 0 then
  ShowMessage('empty string');

Java logical operators:

//Given expressions a, b, c, and d:

if !((a && b) && (c || d)) {

  //Do something.

}

Delphi logical operators:

The Delphi compiler default is to short circuit multi argument boolean expressions when the result is known before the evaluation completes. To disable short circuiting, use the {$B+} compiler directive. To reset it back to the compiler default of short circuting, use the {$B-} compiler directive.

//Given expressions a, b, c, and d:

if Not (a and b) and (c or d) then

  //Do something.

 Delphi Logical Operators  

In Java, you use either the String concatenation + operator or StringBulder class methods such as append. Since Java compilers frequently create intermediate objects when the + operator is used and don't when StringBuilder.append is used, the append method is faster than the + operator.

In general, use the convenience of a + operator when speed is not an issue. For example, when concatenating a small number of items and when code isn't executed very frequently. A decent rule of thumb is to use the + operator for general purpose programming and then optimize the + operator with StringBuilder.append as needed.

System.out.println("Hello" + " " + "Mike.");

StringBuilder myMsg = new StringBuilder();
 

myMsg.append("Hello ");

myMsg.append("Mike.");

 
System.out.println(myMsg);

Use the + operator to concatenate two strings. Use IntToStr to convert an integer to a string and FloatToStr to convert a floating point number to a string.

var 

  FirstName : String; 

  LastName : String;

begin 

  FirstName := 'Mike'; 

  LastName := 'Prestwood';

  ShowMessage('Full name: ' + FirstName + ' ' + LastName);

  ShowMessage(FloatToStr(3.2));

end;

An operation with only one operand (a single input). The Java unary operators are ++, --, +, -, ~, and !.

• + Indicates positive value (numbers are positive without this)
• - Negates an expression
• ++ Increment operator by 1
• -- Decrement operator by 1
• ! Logical complement operator (inverts the value of a boolean)
• ~ Bitwise inversion operator (works on integral data types)

An operation with only one operand (a single input). In Object Pascal, a unary operator has the highest precedence and always precedes its operand (for example, -B), except for the  ^ pointer operator, which follows its operand (for example, P^). In addition to the obvious +, -, and Not operators, Delphi also offers:

The TYPE operator is also a unary operator and is valuated at compile time. The TYPE operator returns the size in bytes of the operand,