WoW:USERAPI substr

This page documents a user-defined function that you can copy and paste into your addon. Replace PREFIX with your addon or lib prefix to avoid conflicts between different versions of these functions.

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Imp strsub. Returns a string starting from start to length characters from start (identical to the PHP function of the same name).

string = <PREFIX>_substr(string, start [, length])

Function Parameters

Arguments

string

String - The subject string.

start

Integer - Start here. 0 and 1 have the same effect. Negative values are acceptable.

length

Integer - Go this many characters and stop. Negative values are acceptable.

Returns

string

The desired piece of the string. If the resulting string is less than 0 characters long (which can only exist in the Twilight Zone), false is returned.

Examples

string = <PREFIX>_substr("World of Warcraft", 2, 4)
string = <PREFIX>_substr("World of Warcraft", -2, -4)
string = <PREFIX>_substr("World of Warcraft", -2, 4)
string = <PREFIX>_substr("World of Warcraft", -2, -1)
string = <PREFIX>_substr("World of Warcraft", 4, -1)

Results

"orld"
false -- error condition: the resulting string is negative in length and, therefore, cannot exist.
"ft"
"f"
"ld of Warcraf"

Code

function <PREFIX>_substr(string, start, length)
    if not string then
        return ''
    end
    -- Sanity checks: make sure integers are integers.
    start = floor(tonumber(start)) or 1
    if length == nil then
        length = strlen(string)
    end
    if length < 0 and start < 0 and abs(length) > abs(start) then
        return false
    end
    if start < 0 then
        start = strlen(string) + (start + 1)
    end
    length = floor(tonumber(length))
    local String = ''
    if length >= 0 then
        String = strsub(string, start, (start - 1) + length)
    else
        String = string
        String = strsub(String, start)
        String = strsub(String, 1, strlen(String) + length)
    end
    return String
end