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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 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.

• int charpos (default: 0 ]): MISSING_PARAM_DESC
• offset (default: 1): An integer representing the offset to charpos.

Returns

• int: value1
• int utf8.charpos: 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

Reference

• Scripting Functions