Numeric for in Lua Programming

In Lua, there are two types of for loops − the numeric for and the generic for.

Syntax

The numeric for uses the following syntax −

for var=exp1,exp2,exp3 do
   something
end

It should be noted that we can write exp1, exp2, exp3 at the same time or we can omit one of them, and the numeric loop will not result in a compile error, though its functionality will change.

Example

Let’s consider a simple variation of a numeric for loop, where we will try to print numbers from 1 to 10.

Consider the example shown below −

for i = 1, 10 do
   print(i)
end

Output

1
2
3
4
5
6
7
8
9
10

Okay, that was simple! How about printing the numbers in a backward order? In that case, we need the exp3 that was mentioned in the syntax of the numeric for loop.

Example

Consider the example shown below which will print the numbers from 10 to 1.

for i = 10, 1, -1 do
   print(i)
end

Output

10
9
8
7
6
5
4
3
2
1

Now, let’s explore a more common and useful case, where we want to iterate over an array in Lua, and print the values that are present inside the array.

Example

Consider the example shown below −

names = {'John', 'Joe', 'Steve'}
for i = 1, 3 do
   print(names[i])
end

Output

John
Joe
Steve