Equal

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=

The symbol = (pronounced “equal”) is used to

• compare two (comparable) values for equality,
• constant declarations (including resourcestring sections), and
• type declarations, as well as
• specifying default values for formal parameters in method declarations.

Furthermore, if enumeration data types are defined with explicit indices, FPC’s Delphi compatibility modes require an equal sign instead of := when specifying the indices.

application

program equalDemo(input, output, stderr);

const
	answer = 42;

resourcestring
	prompt = 'What''s the answer?';

type
	number = longint;

var
	i: number;

begin
	writeLn(prompt);
	readLn(i);
	
	if not (i = answer) then
	begin
		exitCode := 1;
	end;
end.

Be aware of what you compare: When you compare two references, i.e. class or pointer variables, without dereferencing them first, you usually compare two memory addresses, not the actual content at those addresses. Operator overloading may alter this behavior, though. For instance the content of ansistrings can be compared without any special treatment, though internally (transparently) they are realized as pointers.

Note, you usually do not use the equal sign comparison in conjunction with floating-point numbers. Instead one uses math.compareValue.

comparitive remarks

Unlike other programming languages, the symbol is not used to assign a value, for that the character pair := is used. An exception of this are “initialized variables”, where you specify an initial value inside the var section alongside your variable declarations:

program initializedVariable(input, output, stderr);

var
	i: longint;
	response: string = 'Wrong!';

begin
	writeLn('What''s the answer?');
	readLn(i);
	
	if i = 42 then
	begin
		response := 'Right!';
	end;
	
	writeLn(response);
end.

Also, a comparison always results in a boolean value.

ASCII value

In ASCII, the character code decimal 61 (or hexadecimal 3D) is defined to be = (equals sign).

see also

• becomes-operator := assigns values to a variable
• not-equal-operator <> checks for inequality