--- Integer(arg)

    (Fixnum,Bignum)Ѵ̤֤ޤ
    ͡ʸʳΥ֥ȤФƤ to_i ᥽åɤ
    Ѥޤ(ruby 1.7 feature: 1.7 Ǥϡto_int)
    Ѵ̤(IntegerΥ֥饹)Ǥʤ
    㳰 TypeError ȯޤ

    ʸǤäˤϡ0x, 0b, 0 ʤɤƬ˱
    줾 16 ʡ2 ʡ8 ʿȤѴޤ

    ȸʤʤʸ˻ꤷ硢㳰 ArgumentError
    ȯޤ

        p Integer(10.1)       # => 10
        p Integer(10.8)       # => 10
        p Integer("10")       # => 10
        p Integer("10_0_0")   # => 1000
        p Integer("10__0")    # => 100
                              # => invalid value for Integer: "10__0" (ArgumentError) (ruby 1.7 feature)
        p Integer("_10")      # => invalid value for Integer: "_10" (ArgumentError)
        p Integer("10_")      # => invalid value for Integer: "10_" (ArgumentError)
        p Integer("0d10")     # => invalid value for Integer: "0d10" (ArgumentError)
                              # => 10 (ruby 1.7 feature)
        p Integer("010")      # => 8
        p Integer("0o10")     # => invalid value for Integer: "0o10" (ArgumentError) (ruby 1.7 feature)
                              # => 8
        p Integer("0x10")     # => 16
        p Integer("0b10")     # => 2
        p Integer(" \n10\t ") # => 10
        p Integer("")         # => `Integer': invalid value for Integer: "" (ArgumentError)
        p Integer(nil)        # => 0

        p Integer(Object.new) # => cannot convert Object into Integer (TypeError)

    String#hex [String/hex],
    String#oct [String/oct],
    String#to_i [String/to_i] ⻲ȤƤ

