C Simple UTF-16

Author: Árnilsen Arthur Castilho Lopes - 2021

A simple library to deal/support UTF16 strings in pure C.

Features

• Lightweight code
• Lightweight memory usage
• Fast (Memcopy methods)
• Non-external libraries
• No platform dependent functions

UTF-8 vs UTF-16

UTF-8

• Smaller for ascii/english characters (Each character takes only 1 char)
• Bigger for special characters (Chars may variate from 1 byte to 4 chars)
• Harder to work in char level
• Adopted in C language
• Count the real length of an utf-8 would need to iterate through chars to check char-by-char

UTF-16

• Fixed char size for general characters (2 char per char)
• Emotes take only 2 chars (Less than UTF-8)
• Easier to work in char level
• Adopted in Java, C#, etc...
• Count the real length of an utf-16 would only need to find the end of the string

Character	UTF-8 (dec)	UTF-16 (dec)
A (1 char)	65	0 65
Á (1 char)	195 129	0 193
😚 (2 char)	240 159 152 154	216 61 222 26
你 (1 char)	228 189 160	79 96

Basic Example

#include "lib.c"
#include <stdio.h>

void main()
{
	//Create utf16 from C string literals in a fast and simple way
	utf16_string s = utf8_to_utf16("<😚>");
	utf16_string a = utf8_to_utf16("Hillo ");
	utf16_string b = utf8_to_utf16(" world!");
	
	//Manage the strings
	utf16_string c = utf16_string_concat(a, b);
	utf16_string d = utf16_string_insert(c, s, 6);
	
	//Change a char directly
	d[1] = 'e';
	
	//Output string (Convert to utf8 string again)
	printf("%s", utf16_to_utf8(d));
}

Docs

Types

Name	Byte size
utf8_char	1
utf16_char	2
utf32_char	4
utf8_string	length + 1
utf16_string	length * 2 + 2

Functions

//Conversion  UTF16 > UTF8
utf8_string utf16_to_utf8(utf16_string chars);
utf8_string as_c_str(utf16_string s);

//Conversion  UTF8 > UTF16
utf16_string utf8_to_utf16(utf8_string chars);

//UTF8 char util
bool utf8_char_is_single_byte(utf8_char *c);
bool utf8_char_is_double_byte(utf8_char *c);
bool utf8_char_is_triple_byte(utf8_char *c);
bool utf8_char_is_quadruple_byte(utf8_char *c);

//UTF8 string util
size_t utf8_string_length(utf8_string s);

//UTF16 string util
size_t utf16_string_length(utf16_string s);
utf16_string utf16_string_concat(utf16_string a, utf16_string b);
utf16_string utf16_string_insert(utf16_string a, utf16_string b, size_t position);
utf16_string utf16_string_remove(utf16_string s, size_t from, size_t length);
utf16_string utf16_string_substring(utf16_string s, size_t from, size_t length);