红宝石 | StringScanner 窥视函数

StringScanner#peek() : peek()是一个 StringScanner 类方法，它返回对应于字符串[pos, len] 的字符串。

Syntax: StringScanner.peek()

Parameter: StringScanner values
len – length of the string value

Return: a string corresponding to string[pos, len]

示例 #1：

# Ruby code for StringScanner.peek() method
  
# loading StringScanner
require 'strscan'
  
# declaring StringScanner 
c = StringScanner.new("Mon Sep 12 2018 14:39")
  
# peek() method
puts "String Scanner peek form : #{c.peek(3)}\n\n"
  
# peek() method
puts "String Scanner peek form : #{c.peek(6)}\n\n"
  
# peek() method
puts "String Scanner peek form : #{c.peek(9)}\n\n"

输出 ：

String Scanner peek form : Mon

String Scanner peek form : Mon Se

String Scanner peek form : Mon Sep 1

示例 #2：

# Ruby code for StringScanner.peek() method
  
# loading StringScanner
require 'strscan'
  
# declaring StringScanner 
c = StringScanner.new("hellogeeks")
  
# peek() method
puts "String Scanner peek form : #{c.peek(2)}\n\n"
  
# peek() method
puts "String Scanner peek form : #{c.peek(4)}\n\n"
  
# peek() method
puts "String Scanner peek form : #{c.peek(8)}\n\n"

输出 ：

String Scanner peek form : he

String Scanner peek form : hell

String Scanner peek form : hellogee