Converts the UTF-8 codepoint position to byte-string position.

Note

Code point characters beyond the byte value range (0-127) require at least 2 bytes to represent the character.

Syntax

int,​ int utf8.charpos ( string input, [ int charpos = 0, int offset = 1 ] )

Required Arguments

• input: A string character sequence.

Optional Arguments

NOTE: When using optional arguments, you might need to supply all arguments before the one you wish to use.

• charpos (default: 0): An integer representing the beginning position (offset will be added/subtracted).
• offset (default: 1): An integer representing the offset to charpos.

Returns

• int: value1
• int: value2

Returns the integer position as in a byte string and the integer codepoint at this position, nil otherwise.

Code Examples

Example 1 Example 2

shared

This example takes the second codepoint character and shows the byte-string position and the codepoint character code.

local position, codepoint = utf8.charpos("Привет", 2)
print(position, codepoint) -- 3, 1088

shared

This example extracts the first character by calculating the character length with the UTF8 functions and the inbuilt Lua function string.sub, which processes byte strings.

local input = "Привет мир" -- Hello World
local from = utf8.charpos(input, 1) -- 1
local to = utf8.charpos(input, 2) -- 3

local byteLength = to - from
outputConsole(byteLength) -- 2

local character = string.sub(input, from, byteLength)
outputConsole(character) -- П

See Also

UTF8 Library Functions

• utf8.byte
• utf8.char
• utf8.charpos
• utf8.escape
• utf8.find
• utf8.fold
• utf8.gmatch
• utf8.gsub
• utf8.insert
• utf8.len
• utf8.lower
• utf8.match
• utf8.ncasecmp
• utf8.next
• utf8.remove
• utf8.reverse
• utf8.sub
• utf8.title
• utf8.upper
• utf8.width
• utf8.widthindex

Reference

• Scripting Functions