红宝石 |设置添加？函数

添加？是 Ruby 中的一个内置方法，它将给定对象添加到集合中并返回 self.如果对象已经在集合中，则返回 nil。

Syntax: s1.name.add?(object)

Parameters: The function takes the object to be added to the set.

Return Value: It returns self if the object is not in the set and is added, it returns nil if it is already in the set.

示例 1 ：

#Ruby program to illustrate the add ? method
  
#requires the set
require "set"
  
    s1
    = Set[2, 1]
  
#Enters 4 into it
      puts s1.add
    ? (4)
  
#Enters 4 into it
#But set has already 4
          puts s1.add
    ? (4)

输出：

Set: {2, 1, 4}

示例 2 ：

#Ruby program to illustrate the add ? method
  
#requires the set
require "set"
  
    s1
    = Set[5]
  
#Enters 5 into it
#But set has already 5
      puts s1.add
    ? (5)
  
#Enters 8 into it
          puts s1.add
    ? (8)

输出：

Set: {5, 8}

参考：https://devdocs.io/ruby~2.5/set#method-i-add-3F