BEGIN and END Blocks In Ruby

Every Ruby source file can run as the BEGIN blocks when the file is being loaded and runs the END blocks after the program has finished executing. The BEGIN and END statements are different from each other. A program may contain multiple BEGIN and END blocks. If there is more than one BEGIN statement in a program, they are executed in the order If there is more than one END statement, they are executed in the reverse of the order. the first END one is executed last. An open curly brace always come after BEGIN and END keyword.
Syntax:

BEGIN{
Code
.
.
.}
END{
.
.
.}

Below is the example to better understand:
Example :

# Ruby Program of BEGIN and END Block

BEGIN {
   # BEGIN block code
   puts "BEGIN code block"
}

END {
   # END block code
   puts "END code block"
}
   # MAIN block code
puts "GeeksForGeeks"

Output :

BEGIN code block
GeeksForGeeks
END code block

In above example, as we can see BEGIN block code will execute first then Main block code will be executed after that END block code will be executed.
Example :

# Ruby Program of BEGIN and END Block

# BEGIN block
BEGIN {

  a = 4
  b = 3
  c = a + b

   # BEGIN block code
   puts "This is BEGIN block code"
   puts c

}

# END block
END {

  a = 4
  b = 3
  c = a * b

   # END block code
   puts "This is END block code"
   puts c
}

# Code will execute before END block
puts "Main Block"

Output :

This is BEGIN block code
7
Main Block
This is END block code
12

Note :If an END statement is used in a loop Then it is executed more than once.