红宝石 |设置 << 方法

红宝石 |设置 << 方法

<<是 Ruby 中的一个内置方法，它向集合中添加一个元素。

Syntax: s1.name << (element)

Parameters: The function takes an element which is to be added to the set.

Return Value: It adds an element to the set.

示例 1 ：

#Ruby program to illustrate the << method
  
#requires the set
require "set"
  
    s1
    = Set[2, 1]
  
#Prints s1
      puts s1
  
#Enters 4 into it
          s1
      << 4
  
#Prints s1
      puts s1
  
#Enters 4 into it
#But set has already 4
          s1
      << 4
  
#Prints s1
      puts s1

输出：

Set: {2, 1}
Set: {2, 1, 4}
Set: {2, 1, 4}

示例 2 ：

#Ruby program to illustrate the << method
  
#requires the set
require "set"
  
    s1
    = Set[]
  
#Prints s1
      puts s1
  
#Enters 1 into it
          s1
      << 1
  
#Enters 2 into it
      s1
      << 2
  
#Prints s1
      puts s1

输出：

Set: {}
Set: {1, 2}

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