Ruby Modulo Division

问题

So I made a program to do modulo division in Ruby, using a module:

module Moddiv
    def Moddiv.testfor(op1, op2)
        return op1 % op2
    end
end

Program:

require 'mdivmod'
print("Enter the first number: ")
gets
chomp
firstnum = $_
print("Enter the second number: ")
gets
chomp
puts
secondnum = $_
puts "The remainder of 70/6 is " + Moddiv.testfor(firstnum,secondnum).to_s

When I run it with two numbers, say 70 and 6, I get 70 as the output! Why is this happening?

回答1:

It's because firstnum and secondnum are the strings "70" and "6". And String#% is defined - it's the formatted-output operator.

Since "70" is not a format string, it's treated as a literal; so "70" % "6" prints "6" formatted according to the template "70", which is just "70".

You need to convert your input with firstnum = $_.to_i etc.

回答2:

Modulo seems to have trouble with strings, for example, in irb:

"70" % "6" => "70"

try making your return statement:

return op1.to_i % op2.to_i

回答3:

You're grabbing user input as strings, not integers.

"70" % "6"
# => "70"

70 % 6
# => 4

Use .to_i on your parameters and you should be good to go.

来源：https://stackoverflow.com/questions/9808357/ruby-modulo-division