Confusion in Time function output

[arupface]

irb(main):001:0> time=Time.new
=> 2013-01-12 11:22:54 +0530
irb(main):002:0> puts time.to_s
2013-01-12 11:22:54 +0530
=> nil
irb(main):003:0> puts time.ctime
Sat Jan 12 11:22:54 2013
=> nil
irb(main):004:0> puts time.local_time
NoMethodError: undefined method `local_time' for 2013-01-12 11:22:54 +0530:Time
        from (irb):4
        from C:/Ruby193/bin/irb:12:in `<main>'
irb(main):005:0> puts time.localtime
2013-01-12 11:22:54 +0530
=> nil
irb(main):006:0> puts time.strftime("%Y-%m-%d %H:%M:%S")
2013-01-12 11:22:54
=> nil
irb(main):007:0>

Now my confusion is why that "=> nil" coming? what concept here to come it after every time function invokation?

[Taywin]

In your case, your are printing out the local time. The function doesn't return anything after printing out the time, so the irb gets nil as return value and displays it.

[arupface]

in what context the "nil" values will not be returned? any code snippet please?

[Taywin]

If you are not running the script on irb but use ruby to run, then there shouldn't be nil returned from the function call. As I said earlier, irb keeps looking for a returned value. Because the puts does not return a value, it displays nil instead.

PS: Do you know what irb stand for? It is from interactive ruby which is a quick & dirty way to test your script. It is not supposed to be used to run your production script.

[arupface]

thanks for your explanations!

[L7Sqr]

A point of clarification. Every operation in Ruby returns some object. Usually, it is just the result of the last operation. Consider:

irb(main):001:0> def foo &block
irb(main):002:1> block.call
irb(main):003:1> end
=> nil
irb(main):004:0> foo { nil }
=> nil
irb(main):005:0> foo { 42 }
=> 42
irb(main):006:0> foo { Hash.new(0) }
=> {}

The function definition returned a value, it just happens to be nil. Calling foo with different blocks of execution show you that the result of a block of execution is just the last value of that execution. This is true even for assignment.

irb(main):007:0> n = foo { 12 }
=> 12
irb(main):008:0> n
=> 12