why doesn't this ruby code work

Question

here's a practice question - Write a method that will take in a number of minutes, and returns a string that formats the number into hours:minutes .

def time_conversion(minutes)
    hours = minutes / 60
    mins = minutes % 60
    time = hours + ":" + mins
    return time
end

the following are tests to see if this works. if they return true then it means my code works correctly.

puts('time_conversion(15) == "0:15": ' + (time_conversion(15) == '0:15').to_s)
puts('time_conversion(150) == "2:30": ' + (time_conversion(150) == '2:30').to_s)
puts('time_conversion(360) == "6:00": ' + (time_conversion(360) == '6:00').to_s)

sometimes i get true for the first two tests but the third test line shows false even though the code will print out exactly the required.

other times I get the following error:

String can't be coerced into Fixnum (repl):4:in +' (repl):4:in time_conversion' (repl):1:in `initialize'

please assist.

Answer 1

The error mainly refers to this line time = hours + ":" + mins

hours & mins are Fixnum , whereas ":" is String As the error message indicates, "String can't be coerced into Fixnum".

You could either do time = hours.to_s + ":" + minutes.to_s or time = "#{hours}:#{minutes}" .

Answer 2

因为Fixnum#+采用Numeral参数，而不是String 。