LUA delete 2 different characters with gsub

Question

I want to delete two different characters at the beginning and end of my_string with gsub.. But I managed to delete only one..

    local my_string  = "[I wish you a happy birthday]"
    local new_string = bouquet:gsub('%]', '')
    print(new_string)

How can I create the right gsub pattern?

If the characters are present, try `my_string:sub(2,-2)`. – lhf Dec 28 '20 at 10:49 — lhf, Dec 28 '20 at 10:49

score 2 · Answer 1 · answered Dec 28 '20 at 07:20

2

you can do something like this:

local new_string = my_string:match("^%[(.*)]$")

explanation: Match a string that starts with [ and ends with ] and return just what's between the two. For any other strings, it will just return them as is.

answered Dec 28 '20 at 07:20

DarkWiiPlayer

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Wiktor Stribiżew · Answer 2 · 2020-12-28T09:01:16.283

1

You can use

local new_string = my_string:gsub('^%[(.*)]$', '%1')

See this Lua demo. The ^%[(.*)]$ pattern matches

^ - start of string
%[ - a literal [ char
(.*) - captures any zero or more chars into Group 1 (%1 refers to this value from the replacement pattern)
] - a ] char
$ - end of string.

Alternatively, you can use

local new_string = string.gsub(my_string:gsub('^%[', ''), ']$', '')

See this Lua demo online.

The ^%[ pattern matches a [ at the start of the string and ]$ matches the ] char at the end of the string.

If there is no need to check if [ and ] positions, just use

local new_string = my_string:gsub('[][]', '')

See the Lua demo.

The [][] pattern matches either a ] char or a [ char.

edited Dec 28 '20 at 09:01

answered Dec 27 '20 at 22:55

Wiktor Stribiżew

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@bobblebubble This is not a duplicate since the question is not about regex, but about Lua patterns. I replaced the wrong tag. – Wiktor Stribiżew Dec 28 '20 at 01:43
"The `[][]` regex matches"—It's a pattern, not a regex ;) – DarkWiiPlayer Dec 28 '20 at 07:14

score 0 · Answer 3 · answered Dec 29 '20 at 06:28

0

Since you know the basic pattern for gsub, I suggest a easy way to solve you problem.

local new_string = my_string:gsub('%]',''):gsub('%[','')

answered Dec 29 '20 at 06:28

Renshaw

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score 0 · Answer 4 · answered Dec 29 '20 at 12:52

0

So...

do
local my_string="[I wish you a happy birthday]"
local new_string=my_string:gsub('[%[%]]','',2)
print(new_string)
end

...leads to the desired output. The % escapes the [ and ] - Like in other languages the \ do.

answered Dec 29 '20 at 12:52

koyaanisqatsi

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LUA delete 2 different characters with gsub

4 Answers4