Identifiers

• are names given to program name, constants, variables or subprogram names in a Pascal program
• can be classified as standard identifiers and user-defined identifiers
• the syntax diagram of <identifier>

  

  standard identifiers

• have predefined meaning, but they are not reserved words
• can be redefined in the program, once they are redefined, the original predefined meaning are replaced and cannot be applied in the program
• it is not recommended to redefine the standard identifiers which may cause confusion
• a list of standard identifiers :
  
  

  Standard Identifiers
  abs	eoln	randomize	str
  arctan *	exp *	read	text
  assign	false	readln	true
  boolean	input	real	trunc
  char	integer	reset	val
  chr	length	rewrite	write
  close	ln *	round	writeln
  copy	ord	sin *
  cos *	output	sqr	* It is not required in the HKCEE
  eof	random	sqrt

  Remark : Standard identifiers are classified as reserved words in the HKCEE and cannot be used as user-defined variables.

  user-defined identifiers

• names which are made up by the user
• valid user-defined identifiers
  • a combination of letters, digits and underscore ( _ )
  • first character must be a letter
  • reserved words cannot be used
• it is better to use a meaningful name