红宝石 |数组类 first()函数

first()是一个 Array 类方法，它返回数组的第一个元素或数组中的前“n”个元素。

Syntax: Array.first()

Parameter: Array
n – no. of elements

Return: first element of the array or the first ‘n’ elements from the array

示例 #1：

# Ruby code for first() method
  
# declaring array
a = [18, 22, 33, nil, 5, 6]
  
# declaring array
b = [1, 4, 1, 1, 88, 9]
  
# declaring array
c = [18, 22, nil, nil, 50, 6]
  
# first
puts "first : #{a.first(5)}\n\n"
  
# first
puts "first : #{b.first(4)}\n\n"
  
# first
puts "first : #{c.first()}\n\n"

输出 ：

first : [18, 22, 33, nil, 5]

first : [1, 4, 1, 1]

first : 18

示例 #2：

# Ruby code for first() method
  
# declaring array
a = ["abc", "nil", "dog"]
  
# declaring array
b = ["cow", nil, "dog"]
  
# declaring array
c = ["cat", nil, nil]
  
# first
puts "first : #{a.first(5)}\n\n"
  
# first
puts "first : #{b.first(4)}\n\n"
  
# first
puts "first : #{c.first()}\n\n"

输出 ：

first : ["abc", "nil", "dog"]

first : ["cow", nil, "dog"]

first : cat