Table.insert top or bottom of the table?

[ORMtnMan]

Hey everyone,

 

Quick question, when using table.insert does it insert the new entry at the top or bottom of the table index wise?

 

Thanks!

[RoboMat]

table.insert and table.remove both have optional index paramters which allow you to specify at which position to insert / remove a value. Without them, the functions will always operate on the end of the table.

 

table.insert({ 'b', 'c' }, 1, 'a')

 

table.insert would insert 'a' at the first position in the table and automatically shifts all the other values down accordingly.

 

table.remove({ 'a', 'b', 'c' }, 1) 

 

table.remove would remove the first entry and shift the others down in this example.

 

The important thing to keep in mind is that this only works on sequences:

We use the term sequence to denote a table where the set of all positive numeric keys is equal to {1..n} for some integer n, which is called the length of the sequence (see §3.4.6).

A small sidenote. If you have a sequence and want to add / remove entries at the end, I prefer this:

 

t[#t + 1] = 'bar' -- Insert new entry at the end

t[#t] = nil -- Remove last entry in the table

That's because I usually iterate over sequences using the '#' operator:

local foo = { 'a', 'b', 'c' } for i = 1, #foo do    print(foo[i])end

This should be faster than using table.remove / table.insert and ipairs / pairs, but for me it's just personal preference.

[ORMtnMan]

table.insert and table.remove both have optional index paramters which allow you to specify at which position to insert / remove a value. Without them, the functions will always operate on the end of the table.

 

table.insert({ 'b', 'c' }, 1, 'a')

 

table.insert would insert 'a' at the first position in the table and automatically shifts all the other values down accordingly.

 

table.remove({ 'a', 'b', 'c' }, 1) 

 

table.remove would remove the first entry and shift the others down in this example.

 

The important thing to keep in mind is that this only works on sequences:

We use the term sequence to denote a table where the set of all positive numeric keys is equal to {1..n} for some integer n, which is called the length of the sequence (see §3.4.6).

A small sidenote. If you have a sequence and want to add / remove entries at the end, I prefer this:

 

t[#t + 1] = 'bar' -- Insert new entry at the end

t[#t] = nil -- Remove last entry in the table

That's because I usually iterate over sequences using the '#' operator:

local foo = { 'a', 'b', 'c' } for i = 1, #foo do    print(foo[i])end

This should be faster than using table.remove / table.insert and ipairs / pairs, but for me it's just personal preference.

 

 

RoboMat, you are a scholar and a gentleman! This perfectly answers my question!