[RUBY] It's easy to get rid of it, but I've summarized the times method again.

Put this in the corner of your head and read on.

scope

The scope is the range in which the defined variables can be used.

block

do~endOr{ }(Curly braces)The inside is called a block. In addition, in the block|Variable name|　||Variables in (pipeline)~~Block variable~~It is called a block parameter.

STEP1

To make sure you understand it, start here.

num = 1
puts num
#=>1

Such a program appears at the very beginning of variables. To explain it carefully, the numerical value 1 is assigned to the variable num, and it is called by puts. I'm not aware of it, but since it is the scope of the variable num, it can be called with puts.

STEP2

num = 1

3.times do
 puts num
end
#=>1
#  1
#  1

This resulted in puts num being repeated 3 times and a" 1 "3 times. Of note is the scope of the variable num. Variables defined outside do ~ end can be used.

STEP3

3.times do
 num = 1
end
puts num
#=>NameError

The code is similar to STEP2, but I get an error. ↓

NameError (undefined local variable or method num for main:Object)

The simple translation is " num in puts num is not defined". Yes, anything defined inside do ~ end cannot be called outside do ~ end. Actually, a stumbling point! !!

STEP4

num = 1

3.times do|i|
 num = num + i
end
puts num
#=>4

Points to read ① ~~ Block variable ~~ Block parameters start from 0 and increase by 1. In the above example, it is considered that "0" is substituted in the first week, "1" is substituted in the second week, and "2" is substituted in the third week.

(2) The external variables have been rewritten.

If you write it carefully ↓ Week 1 num + 0 => num is defined as 1, so "1 + 0" is assigned to num. 2nd week num + 1 => From the above, num is 1 and since it is the 2nd week, i changes to 1 and "1 + 1" is assigned to num. 3rd week num + 2 => From the above, num is 2, and since it is the 3rd week, i changes to 2 and "2 + 2" is assigned to num.

point

-[x] ~~ Block variable ~~ As the name suggests, block parameters are valid only within blocks. -[x] Variables defined outside the block can be rewritten by processing inside the block.

Finally

Regarding iterative processing, it is a content that you can learn programming at an early stage, and even if you think you understand it, you may not remember the details, so take this opportunity to review it.