Colon

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:

The symbol :, pronounced “colon”, is used in Pascal in several ways:

• in an identifier declaration it separates the type
  • most notably in var sections
  • but also in const sections (in case of explicitely typed constants)
  • procedure and function parameters have a type, too
  • and return values of functions (including operator overloads)
  • as well as properties
  • in general, everywhere where a new identifier associated with some memory, is introduced (also custom structured type definitions)
• in case selectors it closes a match-list
• in label definitions the colon seperates the instruction from the label name
• also some routines, especially the Str, write and writeLn procedures accept further parameters via colon separated arguments
• Offset / segment separation under DOS Mem[$B800:$0000]

The following example shows the most prevalent usage scenarios:

program colonDemo(input, output, stderr);

procedure numberReport(const i: int64);
begin
	case i of
		low(i)..-1:
		begin
			writeLn('Your number is negative. ☹');
		end;
		1..high(i):
		begin
			// right aligns to a width of 24 characters
			writeLn(i:24);
		end;
		else
		begin
			writeLn('You''ve entered zero.');
		end;
	end;
end;

var
	i: int64;

begin
	writeLn('Enter a number:');
	readLn(i);
	numberReport(i);
end.

other remarks

• Colon appears in the assignment operator :=.
• In ASCII the character colon : has the value 58.