Ruby Hash fetch用法及代码示例

Hash＃fetch()是一种Hash类方法，它从哈希中返回给定键的值。没有其他参数，它将引发KeyError异常。

用法：Hash.fetch()

参数：散列值

返回：给定键的哈希值

示例1:

# Ruby code for Hash.fetch() method 
  
# declaring Hash value 
a = { "a" => 100, "b" => 200 } 
  
# declaring Hash value 
b = {"a" => 100} 
  
# declaring Hash value 
c = {"a" => 100, "c" => 300, "b" => 200} 
  
# Handling no key argument 
# fetch? Value 
puts "Hash a fetch form : #{a.fetch("x"){|el| "Not present, #{el}"}}\n\n"

输出：

Hash a fetch form : Not present, x

示例2:

# Ruby code for Hash.fetch() method 
  
# declaring Hash value 
a = { "a" => 100, "b" => 200 } 
  
# declaring Hash value 
b = {"a" => 100} 
  
# declaring Hash value 
c = {"a" => 100, "c" => 300, "b" => 200} 
  
# fetch Value 
puts "Hash a fetch form : #{a.fetch("a")}\n\n"
  
puts "Hash b fetch form : #{b.fetch("a")}\n\n"
  
puts "Hash c fetch form : #{c.fetch("b")}\n\n"

输出：

Hash a fetch form : 100

Hash b fetch form : 100

Hash c fetch form : 200

相关用法

注：本文由纯净天空筛选整理自Kirti_Mangal大神的英文原创作品 Ruby | Hash fetch function。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。