# Unexpected error in time difference

**URL:** <https://www.ruby-forum.com/t/unexpected-error-in-time-difference/154279>\
**Category:** Ruby\
**Created:** [November 27, 2008, 8:34am UTC](https://www.ruby-forum.com/t/unexpected-error-in-time-difference/154279 "2008-11-27T08:34:33Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![phasis](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/e56c9b/32.png) [@phasis](https://www.ruby-forum.com/u/phasis)\
**Post date:** [November 27, 2008, 8:34am UTC](https://www.ruby-forum.com/t/unexpected-error-in-time-difference/154279/1 "2008-11-27T08:34:33Z")

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Hi,

I found some unexpected errors in time difference test.  
Is this a bug or feature?

irb(main):001:0\> Time.now-1  
=\> Thu Nov 27 16:19:35 +0900 2008  
irb(main):002:0\> Time.now -1  
ArgumentError: wrong number of arguments (1 for 0)  
from (irb):2:in `initialize' from (irb):2:in`now’  
from (irb):2  
irb(main):003:0\> Time.now - 1  
=\> Thu Nov 27 16:19:40 +0900 2008  
irb(main):004:0\> t = Time.now  
=\> Thu Nov 27 16:19:48 +0900 2008  
irb(main):005:0\> Time.now-t  
=\> 7.250976  
irb(main):006:0\> Time.now -t  
NoMethodError: undefined method `-@’ for Thu Nov 27 16:19:48 +0900  
2008:Time  
from (irb):6  
from :0  
irb(main):007:0\> Time.now - t  
=\> 11.539909

Regards,

Park H.

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<div class="post-metadata">

**Author:** ![phasis](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/e56c9b/32.png) [@phasis](https://www.ruby-forum.com/u/phasis)\
**Post date:** [November 27, 2008, 8:41am UTC](https://www.ruby-forum.com/t/unexpected-error-in-time-difference/154279/2 "2008-11-27T08:41:00Z")

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On 27.11.2008 08:29, Heesob P. wrote:

> irb(main):003:0\> Time.now - 1  
> =\> 11.539909  
> Works as designed. With Time.now -1 the parser parses this as  
> Time.now(-1). Rule of thumb: use spaces around operators - makes your  
> code also more readable.

Kind regards

robert

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<div class="post-metadata">

**Author:** ![phasis](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/e56c9b/32.png) [@phasis](https://www.ruby-forum.com/u/phasis)\
**Post date:** [November 27, 2008, 8:41am UTC](https://www.ruby-forum.com/t/unexpected-error-in-time-difference/154279/3 "2008-11-27T08:41:35Z")

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If you place parentheses it’s much clearer:

Time.now().-(1)  
vs  
Time.now(-1) # wrong num of args

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<div class="post-metadata">

**Author:** ![phasis](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/e56c9b/32.png) [@phasis](https://www.ruby-forum.com/u/phasis)\
**Post date:** [November 27, 2008, 9:01am UTC](https://www.ruby-forum.com/t/unexpected-error-in-time-difference/154279/4 "2008-11-27T09:01:30Z")

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From: Heesob P. [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)]  
#–

# irb(main):002:0\> Time.now -1

# ArgumentError: wrong number of arguments (1 for 0)

# from (irb):2:in `initialize’

# from (irb):2:in `now’

# from (irb):2

#…

# irb(main):006:0\> Time.now -t

# NoMethodError: undefined method `-@’ for Thu Nov 27 16:19:48

# +0900 2008:Time

# from (irb):6

# from :0

fwiw, i like the dot for its power, emphasis, and lesser surprise.

> Time.now .- 1  
> =\> Fri Nov 28 00:03:38 +0800 2008  
> Time.now .-1  
> =\> Fri Nov 28 00:03:57 +0800 2008  
> Time.now.-1  
> =\> Fri Nov 28 00:04:00 +0800 2008

> t=Time.now  
> =\> Fri Nov 28 00:09:15 +0800 2008  
> -t  
> NoMethodError: undefined method `-@' for Fri Nov 28 00:09:15 +0800 2008:Time from (irb):20 from :0 Time.now -t NoMethodError: undefined method `-@’ for Fri Nov 28 00:09:15 +0800  
> 2008:Time  
> from (irb):21  
> from :0

> Time.now. -t  
> =\> 18.928238