Chr

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The function chr returns the char which has ASCII value b. The signature reads:

function chr(b: byte): char;

The function is used and necessary because of Pascal's strong type safety. With the advent of typecasts a general method became available, though using chr is better style.

A trivial example shall demonstrate the usage of chr:

type
	// modern Latin alphabet has 26 letters
	latinAlphabetCharacterIndex = 0..25;

{$push}
// let compiler generate code ensuring n >= 0 and n < 26
{$rangeChecks on}
function getChrInLatinAlphabet(const n: latinAlphabetCharacterIndex): char;
begin
	getChrInLatinAlphabet := chr(ord('A') + n);
end;
{$pop}

FPC has implemented chr as a compiler intrinsic in_chr_byte.

see also

  • chr in the system unit reference
  • ord does the reverse operation.