how to do it on the left?

[XkPP]

--as an example:
gg.alert(string.format("abcdefg"):sub(7))

this section(:sub) goes to the right, how to do it to the left?

Please help

[CmP]

Direct answer to the question is present in Lua reference manual: 

Quote

string.sub (s, i [, j])

Returns the substring of s that starts at i and continues until j; i and j can be negative. If j is absent, then it is assumed to be equal to -1 (which is the same as the string length). In particular, the call string.sub(s,1,j) returns a prefix of s with length j, and string.sub(s, -i) (for a positive i) returns a suffix of s with length i.

https://www.lua.org/manual/5.3/manual.html#pdf-string.sub

[XkPP]

@CmP

14 hours ago, CmP said:

Direct answer to the question is present in Lua reference manual

Thank you for helping, now it's working