什么样的变量是红宝石ARGV? [英] What kind of variable is ARGV in ruby?
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问题描述
从我已阅读ARGV应该是一个常数,因为它是全部大写,但我可以写一个快速程序,argv中更改的值的一个没有错误。那么什么类型的变量是ARGV?
点ARGV
ARGV [0] =不是原单
p ARGV
解决方案
ARGV是一个常量,但它是一个数组。以恒定数组值可以自由地改变,没有任何警告,像任何常用的数组元素
IRB(主)GT; ARGV.class
= GT;排列
IRB(主)GT; QWERTY = [1,2,3,4]
= GT; [1,2,3,4]
IRB(主)GT; QWERTY [1] = 5
= GT;五
IRB(主)GT; QWERTY
= GT;并[1,5,3,4]
IRB(主)GT; QWERTY<< 6
= GT;并[1,5,3,4,6]
IRB(主)GT; QWERTY = 3
(IRB):警告:已初始化恒QWERTY
= GT; 3
From what I have read ARGV should be a constant since it is all uppercase, but I was able to write a quick program that changed one of the values in ARGV without error. So what type of variable is ARGV?
p ARGV
ARGV[0] = "Not the orginal"
p ARGV
解决方案
ARGV is a constant, but it's an Array. Values in a constant array can be freely changed without any warnings, like any usual array element.
irb(main)> ARGV.class
=> Array
irb(main)> QWERTY = [1, 2, 3, 4]
=> [1, 2, 3, 4]
irb(main)> QWERTY[1] = 5
=> 5
irb(main)> QWERTY
=> [1, 5, 3, 4]
irb(main)> QWERTY << 6
=> [1, 5, 3, 4, 6]
irb(main)> QWERTY = 3
(irb): warning: already initialized constant QWERTY
=> 3
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