problem in checking time format

[pnsreee]

Hi all

I have a time in this format
12:00p,1:20A .

In linux i am using following regexp to check it.
egrep '[0-9]|[0-2]:(0[0-5]|1[0-9])[paPA]' $time.
I am trying to achive this in perl.

Please help me regarding this Issue....

Regards
Naveen

[prn]

Hi Naveen,

Just what are you trying to accomplish? What do you mean "check"? Are you trying to determine whether some string that purports to be a time is a potentially valid time? How did these strings get there? Why do you need to check their format? What kind of "answer" are you looking for? Are you actually trying to convert these strings to useful times or are you just trying to ensure a consistent format? What do you want to do to the ones that don't "check"?

As usual, there's more than one way to do it. Whatever "it" may be. But unless we have a somewhat better idea of what "it" is, I, at least, have no clue about what would help you.

Best Regards,
Paul

[pnsreee]

Hi Paul,
I am checking the string contain the valid time format or not as given above.
These strings are inputs to my program . If these string is in valid formate I go further like conversions to GMT,EST,CST.

Regards
Naveen.P

[prn]

Hi Naveen,

So it looks like you are just asking how to tell if a string matches a regular expression. Right?

#! /usr/bin/perl
use strict;
my $input = '12:45A';
my $timepattern = /[0-9]|[0-2]:(0[0-5]|1[0-9])[paPA]/;
 
if ( $input =~ $timepattern ) {
  print "$input looks like a time.\n";
}
else {
  print "$input does not seem to be a time.\n";
}

On the other hand, if what you really want is a good way to handle strings that (may or may not) contain times in all sorts of formats, then there are good ways to do that. For example, Parsing Dates and Times from Strings is one and from a reasonably well-known source. Another possibilty for a versatile time parser is HTTP::Date, which also looks pretty versatile.

You will often find that it's better to use (or at least study) well-written packages rather than trying to roll your own. Too often people try to do things "the easy way" and fail to take all the cases into account. (I have to admit that I have often been guilty myself.) In fact, using good packages is usually even easier and generally gives you much better coverage for the unexpected cases.

Best Regards,
Paul

[KevinADC]

Paul,

You seem to be one of the "good-guys" so I wish to bring this to your attention. The link you posted: "Parsing Dates and Times from Strings" was a link to pirated material. The material seems to have been deleted but that site posts lots of pirated material.

[prn]

Paul,

You seem to be one of the "good-guys" so I wish to bring this to your attention. The link you posted: "Parsing Dates and Times from Strings" was a link to pirated material. The material seems to have been deleted but that site posts lots of pirated material.

Ouch! Thanks, Kevin! I'll remember that. Now that you mention it, the URL does look suspicious. You're right. I don't want to encourage that sort of thing.

Paul

[miller]

Also, I just wanted to point out that the regex that you were using would not actually validate the most basic of times. Here's one that does what I believe you intended:

#! /usr/bin/perl
 
use strict;
 
my $input = '12:45A';
 
my $timepattern = /^(?:[1-9]|1[012]):[0-5][0-9][paPA]$/;
 
if ( $input =~ $timepattern ) {
    print "$input looks like a time.\n";
 
} else {
    print "$input does not seem to be a time.\n";
}
 

- Miller

[KevinADC]

I think you need to use "qr" to properly quote the regular expression otherwise it will not work.

#! /usr/bin/perl
use strict;
my $input = '12:45A';
my $timepattern = qr/^(?:[1-9]|1[012]):[0-5][0-9][paPA]$/;
if ( $input =~ $timepattern ) {
   print "$input looks like a time.\n";
} else {
   print "$input does not seem to be a time.\n";
}

example:

#! /usr/bin/perl
use strict;
my $input = '999991:45A';
my $timepattern = /^(?:[1-9]|1[012]):[0-5][0-9][paPA]$/;
if ( $input =~ $timepattern ) {
   print "$input looks like a time.\n";
} else {
   print "$input does not seem to be a time.\n";
}

output:

999991:45A looks like a time

#! /usr/bin/perl
use strict;
my $input = '999991:45A';
my $timepattern = qr/^(?:[1-9]|1[012]):[0-5][0-9][paPA]$/;
if ( $input =~ $timepattern ) {
   print "$input looks like a time.\n";
} else {
   print "$input does not seem to be a time.\n";
}

output:

999991:45A does not seem to be a time.

[miller]

I think you need to use "qr" to properly quote the regular expression otherwise it will not work.

Nod. I was just testing you.... You passed! :)

- M