Announcement

**Davidk** · 09-14-2010, 09:13 AM

Re: inverse of ctime()

Because the format of the character string is known you can pick off the pieces of the string and reconvert into real date and time values.

The documention refers to then ending value of the string as "P" which is, I suppose, for am or pm but it looks like it's not valid anymore... it looks like it's just another value for seconds and that the time is being converted to a 24 hour clock. The documentation needs to be updated.

If someone hasn't written one already I'll put one together a bit later this morning.

**tarlachmoorhouse** · 09-14-2010, 09:17 AM

Re: inverse of ctime()

Originally posted by Davidk View Post

Because the format of the character string is known you can pick off the pieces of the string and reconvert into real date and time values.

The documention refers to then ending value of the string as "P" which is, I suppose, for am or pm but it looks like it's not valid anymore... it looks like it's just another value for seconds and that the time is being converted to a 24 hour clock. The documentation needs to be updated.

If someone hasn't written one already I'll put one together a bit later this morning.

Thanks for this, I'm happy to do a recursive bit of chopping to do it, just wondered if there was a built in command that did it

Ta

John

**CALocklin** · 09-14-2010, 10:09 AM

Re: inverse of ctime()

You may have figured this out already but after getting the characters turned around and separated as necessary, you can use convert_type() to change it to an actual date/time type.

?convert_type( "09/14/2010 10:30:25.909", "T" )
= 09/14/2010 10:30:25 90 am

**tarlachmoorhouse** · 09-14-2010, 10:30 AM

Re: inverse of ctime()

Originally posted by CALocklin View Post

You may have figured this out already but after getting the characters turned around and separated as necessary, you can use convert_type() to change it to an actual date/time type.

?convert_type( "09/14/2010 10:30:25.909", "T" )
= 09/14/2010 10:30:25 90 am

I've used

Code:

dim tempdatetime as T
tempdatetime = time_var(val(left(t.my_value,4)),val(mid(t.my_value,5,2)),val(mid(t.my_value,7,2)),val(mid(t.my_value,9,2)),val(mid(t.my_value,11,2)),val(mid(t.my_value,13,5))/100)

where t.myvalue is the field containing the output of ctime(a date time)

time_var(year,month,day,hour,minute,second) where all the values are integers execpt seconds where it goes to 3 decimal places (xx.yyy seconds the last 5 digits of the ctime output)

Thanks for the suggestions

John

**Ton Spies** · 09-15-2010, 03:18 PM

The inverse of ctime()

Originally posted by tarlachmoorhouse View Post

what goes back the other way, ie would convert "20100914103025909" to a date time value ?

I think this

Code:

tempdatetime = eval(mask(t.my_value,"time_var(    ,  ,  ,  ,  ,  )"))

See explanation in the IW with European time: dd-mm-yyyy
this should work also for mm-dd-yyyy.

Regards

Ton

**tarlachmoorhouse** · 09-15-2010, 03:29 PM

Re: The inverse of ctime()

Originally posted by Ton Spies View Post

I think this

Code:

tempdatetime = eval(mask(t.my_value,"time_var(    ,  ,  ,  ,  ,  )"))

See explanation in the IW with European time: dd-mm-yyyy
this should work also for mm-dd-yyyy.

Regards

Ton

Thanks Ton a much cleaner solution than my multiple mid's

Regards

John

**Ton Spies** · 09-15-2010, 05:03 PM

Re: inverse of ctime()

Hi John,

Quick response, did you test it? Also in mm-dd-yyyy okay?

I used to do the same way as you did -and sometimes you must - but Stan Mathews was my teacher in nesting functions to get them in one line.

Ton

**aRob** · 09-15-2010, 05:30 PM

Re: inverse of ctime()

Ton,

Very impressive.

**CALocklin** · 09-15-2010, 10:24 PM

Re: inverse of ctime()

Learned something new - I've never used timevar() before. That's definitely easier and cleaner.

However - just an FYI - like so many things in programming there is a trade off. Using the simpler timevar() takes over 20 times longer than "cutting up the string" and using convert_type(). If it only needs to be done once, I'd use the timevar() method. But if you are running it in a loop that extra time may make a noticeable difference. Unfortunately there's another trade-off, the convert_type() function seems to ignore the decimals. So, you're stuck with the slower time using timevar() if the decimals are important.

Code:

 
[COLOR=blue]'09/15/2010 21:36:10.890[/COLOR]
c_var = "20100915213610890"
 
stime = now()
FOR qx = 1 to 1000
    result = eval( mask(C_var,"time_var(    ,  ,  ,  ,  ,  .   )"))
NEXT
ui_msg_box( "TIME", "Time: " + ltrim(str(now()-stime,10,3 )) +crlf(2)+ result )
 
stime = now()
FOR qx = 1 to 1000
    result = convert_type( substr(c_var,5,2)+"/"+substr(c_var,7,2)+"/"+left(c_var,4)+" "+substr(c_var,9,2)+":"+substr(c_var,11,2)+":"+substr(c_var,13,2)+"."+right(c_var,3), "T" )
NEXT
ui_msg_box( "TIME", "Time: " + ltrim(str(now()-stime,10,3 )) +crlf(2)+ result )
 
stime = now()
FOR qx = 1 to 1000
    result = convert_type( mid(c_var,5,2)+"/"+mid(c_var,7,2)+"/"+left(c_var,4)+" "+mid(c_var,9,2)+":"+mid(c_var,11,2)+":"+mid(c_var,13,2)+"."+right(c_var,3), "T" )
NEXT
ui_msg_box( "TIME", "Time: " + ltrim(str(now()-stime,10,3 )) +crlf(2)+ result )
 
[COLOR=blue]'I also decided to try this. It's somewhere between the first "timevar()" method and the last method using "mid()".[/COLOR]
stime = now()
FOR qx = 1 to 1000
    result = time_var( val(left(c_var,4)), val(substr(c_var,5,2)), val(substr(c_var,7,2)), val(substr(c_var,9,2)), val(substr(c_var,11,2)), val(right(c_var,6)) )
NEXT
aims_msg_box( "TIME", "Time: " + ltrim(str(now()-stime,10,3 )) +crlf(2)+ result )

So, for speed, do it the hard way by changing the string around using substr() and convert_type() but for simplicity when there's no loop or a short loop use timevar().

EDIT:
I just realized John had used mid() instead of substr(). BIG mistake if you are running in a loop and worried about time. Just changing my equation from substr() to mid() almost makes it take as long as using timevar(). Apparently the mid() function is just a wrapper for the substr() function and wrapper functions are always much slower. (I added the "mid()" version to the code above.)

**Ton Spies** · 09-16-2010, 07:41 AM

Re: inverse of ctime()

Thank you Rob.
Made it with pleasure.

Hi Cal

Thank you for your investigations and examples.

Have you seen that decimals are also ignored with the time_var function?
They should not, but get weird when the decimals are given to the function like 10890/100.
However the syntax is okay, I think the function does not interpret 10890/100 as a calculation.
Maybe at Alpha they can see why decimals are ignored beacuse formal it's not proper.
I tried some varations but the differences are small so it is not important at least for me.

Code:

result = time_var(2010,09,15,21,36,10890/100)
?? result
	15-09-2010 09:36:48 00 pm
result = time_var(2010,09,15,21,36,10.890)
?? result
	15-09-2010 09:36:10 00 pm
result = time_var(2010,09,15,21,36,10)
?? result
	15-09-2010 09:36:10 00 pm

The speed can be an issue as you said. I tried this:

Code:

stime = now()
FOR qx = 1 to 1000
    Dt_result = time_var(2010,09,15,21,36,18)
NEXT
Tm_result = "Time: " + ltrim(str(now()-stime,10,3 ))
?? Tm_result
	"Time: 2.472"
?? Dt_result
	15-09-2010 09:36:18 00 pm

So time_var is a time consuming function.
I did not look at that function for speed did not know that but for ease.

Well, you know the diffence between our cultures with date, decimal and currency signs
So with this line I have to replace mm-dd to dd-mm and "/ " to "-".

?? convert_type( substr(c_var,7,2)+"-"+substr(c_var,5,2)+"-"+left(c_var,4)+" "+substr(c_var,9,2)+":"+substr(c_var,11,2)+":"+substr(c_var,13,2)+"."+right(c_var,3), "T" )

and when you make a mistake there is no output and no warning. Try it with this line above in the IW.

Therefore I constructed this one-line-statement - see post #6 - as useful for international usage.

Ton

**Steve Andrews** · 09-16-2010, 10:15 AM

Re: inverse of ctime()

I haven't timed it, but another way to parse it up is as follows:

Code:

cTm = "20100914103025909"
cTm2 = mask(cTm,"    -  -  -  -  -  -   ")

?cTm2
= "2010-09-14-10-30-25-909"

?tagged_pattern("1-2-3-4-5-6-7","2/3/1 4:5:6 7",cTm2)
= "09/14/2010 10:30:25 909"

The mask() and tagged_pattern() could be combined for a single expression.

Steve

**CALocklin** · 09-16-2010, 11:21 AM

Re: inverse of ctime()

Originally posted by Ton Spies View Post

...and when you make a mistake ...

Yeah, that happened to me once, too.:D

**Ton Spies** · 09-18-2010, 05:46 AM

Re: inverse of ctime()

Originally posted by Steve Andrews View Post

The mask() and tagged_pattern() could be combined for a single expression.

Hi Steve,

Thank you for your contribution because with a fabulous time this now is the quickest and thus far best solution as inverse of ctime(). (Speedtime tested like Cal' way so without the dim's = 0.055!)

Dim C_var as C = ctime(now())
Dim T_result as T = convert_type(tagged_pattern("1-2-3-4-5-6-7","3-2-1 4:5:6 7",mask(C_var," - - - - - - ")) , "T" ) ' for dd-mm-yyyy OR
Dim T_result as T = convert_type(tagged_pattern("1-2-3-4-5-6-7","2/3/1 4:5:6 7",mask(C_var," - - - - - - ")) , "T" ) ' for mm/dd/yyyy

Originally posted by CALocklin View Post

Unfortunately there's another trade-off, the convert_type() function seems to ignore the decimals. So, you're stuck with the slower time using timevar() if the decimals are important.

Hi Cal,

Please note that there are 3 decimals (for tag7) but to get proper results, use only the first 2.
So ignore the last position of the string when created by the ctime function. (As shown above)

I also had problems with the decimals in the time_var function (only non US) but Selwyn fixed that for the next release.
So as far I know our decimals-problem has gone then.

Ton

**tarlachmoorhouse** · 09-19-2010, 01:33 PM

Re: inverse of ctime()

As the original poster I've been following this with interested, but as I simply use this to load and save globals variables to a table when the programme loads and at other time, I wasn't to worried about the speed of operation.

However Tom's last post made me realise that we may have a problem as my solutions don't take into account that the UK / US date format issue, ie mm/dd/yyyy and dd/mm/yyyy.

I'm just wondering if there is a better solution than using ctime to my over all problem, I want to convert a datetime variable to a character format so I can save it in a character field, and then 're-constitute' it into a datetime variable at a later time.

I looking at whether it might be better to to use one conversion to re-convert the date part which would deal with the internationaisation of it, and a second re-conversion to handle the time part and then combine them into the datetime.

Ta

John

Announcement

The Alpha Software Forum Participation Guidelines

inverse of ctime()

inverse of ctime()

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment