[Ruby] Method definition summary

Summary of description about method definition of ruby.

The method definition method is basically similar to python. Ruby does not require ":" at the end of the first line. Need "end" at the end.

It is a keyword argument using ":", and a value can be passed by the argument name.

table of contents

[Method definition](#method definition)
[Call Method](#Call Method)
[Pass arguments](#pass arguments)
[Return value](#Return value)
[Use return value in method](Use return value in # method)
[Return boolean value in return value](#Return boolean value in return value)
[Return ends the method](#return ends the method)
[Return value and if statement (pass the return value to the if statement)](# Return value and if statement Pass the return value to the if statement)
[Use return and if statements in return value and if statement methods](#Use return and if statements in return value and if statement methods)
[Keyword Argument](#Keyword Argument)

Method definition

`python`


def method name
processing
end

└ end required

Method call

Method name └ () Not required * When there is no argument

`Method example`


def hello
 puts "Hello"
end

hello

#output
Hello

Pass arguments

`python`


def method name(Argument name 1,Argument name 2,,)
processing
end

Method name(Argument name 1,Argument name 2,,)

└ Cannot be called without arguments (error) └ Match the number of arguments (error if not matched) └ Argument name can be used only in the defined method (scope)

Return value

return value └ Replace the value with the method. └ Values are strings, formulas, etc.

Use the return value in the method

`python`


def method name
return value
end

`Return value example`


def divide(a,b)
  return a/b
end

puts add(10,5)

value=add(10,5)
puts "The division result is#{value}is"

#output
2
The division result is 2

Returns a boolean value as a return value

return conditional expression └ The result of the conditional expression is returned as true / false

Method name? (Argument name) └ Add "?" To the method that returns the boolean value (true / false). └ As a convention

`Method that returns 0 or more as a boolean value`


def positive?(value)
 return value > 0
end

puts positive?(10)
puts positive?(-3)

#output
true
false

The method ends with return

The processing after return in the method is not executed.

`python`


def divide(a,b)
  return a/b
  puts "Divided"
end

divide(10,5)

#output
2

"Puts" divided "" just below return is not executed.

Return value and if statement (pass the return value to the if statement)

Set a boolean value in the return value of the method and call the method with the conditional expression of the if statement.

`python`


#Method that returns a boolean value
def discount?(price)
 return price >= 1000
end


price=800

if discount?(price)
  puts "10%Discount. the price is#{price*0.9}is."
else 
  puts "after#{1000-price}10 in yen%It is a discount"
end


#output
10 for another 200 yen%It is a discount

Return value and if statement (use return and if statement in the method)

Use if statements and return values in methods.

`python`


#Discount consumption tax over 1000
def total_value(price)
 if price >= 1000
   return price
 end 
 return 1000*1.1

end

puts "The payment amount is#{total_value(800)}It's a yen"

#output
The payment amount is 880 yen

Keyword arguments

Specify the value by the name of the argument. def method name (argument name A :, argument name B: ,,,) └ Add ":" after the argument name └ No change in processing

Method name (argument name B: value, argument name A: value ,,,) └ Match with the argument name defined in the method └ Add ":" after the argument name

`python`


def user(name:, age:, gender:, word:)
  puts "#{name}Is your age#{age}is"
  puts "what is your gender#{gender}is"
  puts "The habit is "#{word}"is"
end

user(gender:"male", name:"JoJo", age:"17", word:"Oraora Oraoraoraora")

#output
JoJo is 17 years old"
Gender is male"
The habit is "Oraoraoraoraoraoraora""