UTF8CodepointCount function

Declaration

function UTF8CodepointCount(const s: string): SizeInt

Arguments

Function result

Integer value with the number of valid codepoints including combining characters.

Description

UTF8CodepointCount is an overloaded SizeInt function used to determine the number of UTF-8 codepoints found in the specified value. It is similar to the UTF8Length routine, but excludes any invalid codepoints found in the input value from the count in the return value. The overloaded variants allow the input value to be specified using either the String or the PChar type.

UTF8CodepointCount iterates over the byte values in the s or p arguments, and increments the return value when a valid UTF-8 codepoint is found. UTF8CodepointLen (in system.pp) is called to the get the size for each of the UTF-8 codepoints. Valid codepoints include those represented using combining characters. The process is repeated until all of the bytes in the input value have been examined, or until a codepoint with a length of zero (0) is encountered.

The return value is zero (0) if the s or p arguments are empty, or when the ByteCount argument is zero (0).

For example:

// var
//   Utf8Str, InvalidUtf8Str: String;
//   Cnt, Len: Integer;

{A macron (decomposed)}
Utf8Str := 'A' + #$CC#$84;

{invalid single byte UTF-8}
InvalidUtf8Str := #$C0#$C1#$F5#$F6#$F7#$F8#$F9#$FA#$FB#$FC#$FD#$FE#$FF;

Cnt := UTF8CodePointCount(Utf8Str); // Cnt = 2
Len := UTF8Length(Utf8Str); // Len = 2

Cnt := UTF8CodePointCount(InvalidUtf8Str); // Cnt = 0
Len := UTF8Length(InvalidUtf8Str); // Len = 13

Cnt := UTF8CodePointCount(InvalidUtf8Str + Utf8Str); // Cnt = 2
Len := UTF8Length(InvalidUtf8Str + Utf8Str); // Len = 15

Added in LazUtils version 4.0.

See also

• UTF8Length
• UTF8CodepointSize
• UTF8LengthFast
• UTF8CharacterLength
• UTF8CodepointLen