This library is an iterator for UTF8 chains, in addition to converting characters from UTF8 to Unicode and vice versa.

I have created a document in Spanish that explains how this library works inside. You can read it and download it in PDF from this link. Document in Google Doc

Using UTF8 Iterator is very easy, it consists of a structure and two functions.

#include "utf-8.h"
#include <stdio.h>

int main() {

    const char* String = "Hello World, こんにちは世界, привет мир.";

    utf8_iter ITER;
    utf8_init(&ITER, String);

    while (utf8_next(&ITER)) {

        printf("Character: %s \t Codepoint: %u\n", utf8_getchar(&ITER), ITER.codepoint);

    }
    return 0;
}

utf8_iter is the structure, and contains important and useful data.

• ptr is the original pointer to the character string, it is assigned by utf8_init().
• codepoint is the current character in Unicode.
• size is the size in bytes of the current character.
• position is the current position in the string.
• next is the next position in the string.
• count is the number of characters currently.
• length is the length of the string with strlen()

utf8_init(iter, string) is used to start or restart the iterator. The first argument is a pointer to the Iterator, and the second argument is the character string.

utf8_initEx(iter, string, length) works the same as utf8_init, but allows the user to set a maximum length for the string.

utf8_next(iter) checks the string, the size of the next character and converts the character to Unicode. Return: 1 -> Continue, 0 -> End or Error.

utf8_previous(iter) check the string, the size of the previous character and converts the character to Unicode. Return: 1 -> Continue, 0 -> End or Error.

utf8_getchar(iter) allows to obtain the character in UTF8 (char*) in the Iterator position.

These functions do not require the use of the Iterator:

• utf8_len(string) returns the number of unicode characters in the string. It is different from strlen()
• utf8_nlen(string, end) returns the number of unicode characters in the string to end. It is different from strnlen()
• utf8_to_unicode(char*) returns the codepoint in unicode.
• unicode_to_utf8(codepoint) returns the pointer to a string with the character in UTF8.

For internal use or advanced users:

• utf8_charsize(char*) returns the size in bytes of the provided character.
• unicode_charsize(codepoint) returns the size in bytes that a Unicode character occupies in a UTF8 string.
• utf8_converter(char*, size) this function converts a UTF8 character to Unicode. This function does not perform the size check. Requires the user to provide the character size.
• unicode_converter(codepoint, size) this function converts a Unicode character to UTF8. Like utf8_converter(...), it requires you to provide the size of the character.

To compile in GCC, use the following commands within the library folder:

mkdir Build
gcc -Isource/ -Wall main/main.c source/utf-8.c -o build/utf-8

In Windows: build\utf-8.exe
In Mac and Linux: ./build/utf-8

Tested with GCC, MinGW, XCode and Visual Studio 2017.

You can report a problem in English or Spanish.

Link to GitHub: https://github.com/adrianwk94/utf8-iterator

UTF8 Iterator is distributed with an MIT License. You can see LICENSE for more info.