Generic for in Lua Programming

The generic for in Lua allows us to iterate over the values in an iterator fashion; it is much more powerful even though it looks simple. The Lua library has plenty of iterators, over which we can use the generic for loop.

Syntax

for i, v in pairs(x) do
      ...
      ...
end

The i in the above syntax denotes the index of the items we are going to iterate over only by one, and the v denotes the actual values of those items. The x is the iterable item over which we are iterating, it can be a list, array, or map.

Example

Now let’s consider a simple example where we will try to iterate over the items of an array and will print the index of the items in the array.

Consider the example shown below −

a = {11,12,13,14,15,16,17}

for i, v in pairs(a) do
   print(i)
end

Output

1
2
3
4
5
6
7

Now, instead of printing the index, let’s print both the indexes and values that are present inside the array.

Example

Consider the example shown below −

a = {11,12,13,14,15,16,17}

for i, v in pairs(a) do
   print(i)
   print(v)
end

Output

1
11
2
12
3
13
4
14
5
15
6
16
7
17

It should be noted that we can also omit the variable i or v depending on our use-case. Consider a case where we just need to print the value of the array. In that case, we can remove the identifier for index from the generic for loop.

Example

Consider the example shown below −

a = {11,12,13,14,15,16,17}

for _, v in pairs(a) do
   print(v)
end

Output

11
12
13
14
15
16
17

Mukul Latiyan

Updated on: 01-Dec-2021

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