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Programming-Idioms

  • Lisp
  • Pascal
  • Python

Idiom #340 Last character of string

Assign to c the value of the last character of the string s.

Explain the type of c, and what happens if s is empty.

Make sure to properly handle multi-bytes characters.

c = s[-1]

Exception IndexError is raised if s is empty. c is a string of length 1, which may contain any valid unicode character.
LazUtf8
function GetLastUtfCodePoint(const S: String): String;
var
  p: PChar;
  PLen: PtrInt;
begin
  Result := '';
  p := UTF8CodepointStart(PChar(S), Length(S), Utf8Length(S) - 1);
  PLen := UTF8CodepointSize(p);
  Result := p;
  SetLength(Result,PLen);
end; 

var
  s: string;
begin
  c := GetLastUtfCodePoint(s);
end.

This is a solution for UTF8 encoded strings.
The type of c is String, also encoded as UTF-8.
An empty string is returned if s is empty.
{$modeswitch unicodestrings}
c := s[Length(s)];

The {$modeswitch unicodestrings}
makes the compiler use unicodestrings, whereas by default strings are single byte encoded.
c is of type WideChar (2 bytes wide)
If s is empty an exception will be raised, since the code then accesses s[0], and strings are 1-based in Pascal
char c = s[^1];
New implementation...
< > ⌨
programming-idioms.org 
c = s[-1]
function GetLastUtfCodePoint(const S: String): String;
var
  p: PChar;
  PLen: PtrInt;
begin
  Result := '';
  p := UTF8CodepointStart(PChar(S), Length(S), Utf8Length(S) - 1);
  PLen := UTF8CodepointSize(p);
  Result := p;
  SetLength(Result,PLen);
end; 

var
  s: string;
begin
  c := GetLastUtfCodePoint(s);
end.
c := s[Length(s)];
char c = s[^1];
final c = s[s.length - 1];
r := []rune(s)
c := r[len(r)-1]
c, _ := utf8.DecodeLastRuneInString(s)
lastChar :: String -> Char
lastChar s
    | s=="" = ""
    | otherwise = s !! (length s - 1)
int n = s.length(), i = n - 1;
if (isSurrogate(s.charAt(i))) --i;
String c = s.substring(i);
$c = substr($s, -1, 1);
c = s[-1]
let c = s.chars().last().unwrap();