Help formatting a UTC TImestamp

Help formatting a UTC TImestamp

[Guy Baumann]

I am trying to format a timestamp from an api.  It is the format "2011-03-24T20:30:47Z"

what I want to produce is something like this
(strftime "%d %b %g " (localtime (current-time)) )

However I am unable to work out how to do this, have tried using string->date with results below

Enter `,help' for help.
scheme@(guile-user)> (define date "2011-03-24T20:30:47Z")
scheme@(guile-user)> (use-modules (srfi srfi-19))
scheme@(guile-user)> (string->date "~Y-m-dT~H:~M:SZ" date)
srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type bad-date-format-string: "2011-03-24T20:30:47Z"

Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
scheme@(guile-user) [1]> (string->date date "~Y-m-dT~H:~M:SZ")
srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type bad-date-format-string: "~Y-m-dT~H:~M:SZ"

Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
scheme@(guile-user) [2]> (string->date date "~Y-m-dT~H:~M:SZ")
srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type bad-date-format-string: "~Y-m-dT~H:~M:SZ"

Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
scheme@(guile-user) [3]> (string->date "2000" "~Y")
srfi/srfi-19.scm:571:22: In procedure encode-julian-day-number:
srfi/srfi-19.scm:571:22: In procedure -: Wrong type: #f

thanks for any help

//guy

Help formatting a UTC Timestamp

[Guy Baumann]

I am trying to format a timestamp from an api. It is sent in the
 format "2011-03-24T20:30:47Z"

what I want to output is something like this
(strftime "%d %b %g " (localtime (current-time)) )

However I am unable to work out how to do this, have tried using
 string->date with results below

Enter `,help' for help.
scheme@(guile-user)> (define date "2011-03-24T20:30:47Z")
scheme@(guile-user)> (use-modules (srfi srfi-19))
scheme@(guile-user)> (string->date "~Y-m-dT~H:~M:SZ" date)
srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type bad-date-format-string: "2011-03-24T20:30:47Z"

Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
scheme@(guile-user) [1]> (string->date date "~Y-m-dT~H:~M:SZ")
srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type bad-date-format-string: "~Y-m-dT~H:~M:SZ"

Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
scheme@(guile-user) [2]> (string->date date "~Y-m-dT~H:~M:SZ")
srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type bad-date-format-string: "~Y-m-dT~H:~M:SZ"

Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
scheme@(guile-user) [3]> (string->date "2000" "~Y")
srfi/srfi-19.scm:571:22: In procedure encode-julian-day-number:
srfi/srfi-19.scm:571:22: In procedure -: Wrong type: #f

thanks for any help

//guy

Re: Help formatting a UTC Timestamp

[tomas]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Tue, Feb 14, 2017 at 12:27:16PM +0000, Guy Baumann wrote:
> I am trying to format a timestamp from an api. It is sent in the
>  format "2011-03-24T20:30:47Z"
> 
> what I want to output is something like this
> (strftime "%d %b %g " (localtime (current-time)) )
> 
> However I am unable to work out how to do this, have tried using
>  string->date with results below
> 
> Enter `,help' for help.
> scheme@(guile-user)> (define date "2011-03-24T20:30:47Z")
> scheme@(guile-user)> (use-modules (srfi srfi-19))
> scheme@(guile-user)> (string->date "~Y-m-dT~H:~M:SZ" date)
> srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type bad-date-format-string: "2011-03-24T20:30:47Z"

You got the args reversed: it's first the date string, then the
template. Besides, you forgot a couple of tildes in your template
(e.g. it's "~m" and not just "m" and so on). Lastly, the template
for the zone offset is "~z" (a small z). The "big Z" in your input
string is just a concrete zone (afaik UTC).

This works:

  scheme@(guile-user)> (define mydate "2011-03-24T20:30:47Z")
  scheme@(guile-user)> (string->date mydate "~Y-~m-~dT~H:~M:~S~z")
  $3 = #<date nanosecond: 0 second: 47 minute: 30 hour: 20 day: 24 month: 3 year: 2011 zone-offset: 0>

hth
- -- t
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iEYEARECAAYFAlii/LMACgkQBcgs9XrR2kbySACfY3yqQgFw4XWIBZo1Nif8exJ1
jwUAn04XBldYBIWDDhheEjI1nLbFbjhm
=MJ3B
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Re: Help formatting a UTC Timestamp

[Chris Vine]

On Tue, 14 Feb 2017 12:27:16 +0000
Guy Baumann <guy@gammarus.co.uk> wrote:
> I am trying to format a timestamp from an api. It is sent in the
>  format "2011-03-24T20:30:47Z"
> 
> what I want to output is something like this
> (strftime "%d %b %g " (localtime (current-time)) )
> 
> However I am unable to work out how to do this, have tried using
>  string->date with results below
> 
> Enter `,help' for help.
> scheme@(guile-user)> (define date "2011-03-24T20:30:47Z")
> scheme@(guile-user)> (use-modules (srfi srfi-19))
> scheme@(guile-user)> (string->date "~Y-m-dT~H:~M:SZ" date)
> srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type
> bad-date-format-string: "2011-03-24T20:30:47Z"
> 
> Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
> scheme@(guile-user) [1]> (string->date date "~Y-m-dT~H:~M:SZ")
> srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type
> bad-date-format-string: "~Y-m-dT~H:~M:SZ"
> 
> Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
> scheme@(guile-user) [2]> (string->date date "~Y-m-dT~H:~M:SZ")
> srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type
> bad-date-format-string: "~Y-m-dT~H:~M:SZ"
> 
> Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
> scheme@(guile-user) [3]> (string->date "2000" "~Y")
> srfi/srfi-19.scm:571:22: In procedure encode-julian-day-number:
> srfi/srfi-19.scm:571:22: In procedure -: Wrong type: #f

You haven't got the escapes quite right.  This will work:

  (string->date date "~Y-~m-~dT~H:~M:~SZ")

As will this with skipping, given that your example uses numeric values:

  (string->date date "~Y~m~dT~H~M~SZ")

Chris