红宝石 |哈希压缩！（）函数

袖珍的！ ()是一个 Hash 类方法，它在从 Hash 中删除所有“nil”值元素（如果有）后返回 Hash。如果 Hash 中没有 nil 值，则返回 nil 值。

Syntax: Hash.compact!()

Parameter: Hash to remove the ‘nil’ value from.

Return: removes all the nil values from the Hash.
nil – if there is no nil value in the Hash

示例 #1：

# Ruby code for compact!() method
# showing how to remove nil values
  
# declaring Hash value
a = {a:100, b:nil}
  
# declaring Hash value
b = {a:100, c:nil, b:200}
  
# declaring Hash value
c = {a:100}
  
  
# removing nil value from Hash
puts "removing nil value : #{a.compact!}\n\n"
  
# removing nil value from Hash
puts "removing nil value : #{b.compact!}\n\n"
  
# removing nil value from Hash
puts "removing nil value : #{c.compact!}\n\n"

输出 ：

removing nil value : {a:100}

removing nil value : {a:100, b:200}

removing nil value : {}

示例 #2：

# Ruby code for compact!() method
# showing how to remove nil values
  
# declaring Hash value
a = { "a" => nil, "b" => 200 }
  
# declaring Hash value
b = {"a" => 100}
  
# declaring Hash value
c = {"a" => 100, "c" => nil, "b" => 200}
  
# removing nil value from Hash
puts "removing nil value : #{a.compact!}\n\n"
  
# removing nil value from Hash
puts "removing nil value : #{b.compact!}\n\n"
  
# removing nil value from Hash
puts "removing nil value : #{c.compact!}\n\n"

输出 ：

removing nil value : {b:200}

removing nil value : 

removing nil value : {a:100, b:200}