[SOLVED] Checking the format of a date

[cpd]

Baisically i want to check the format of a date.

 

say the format must be dd/mm/yyyy

 

I want to check its in that format...How do i do this?

[Caesar]

Well, your question wasn't very specific. What exactly are you checking? User input? A record stored in a database? A string?

 

 

Anyway...assuming it's a string or something manually entered in a form (Bad idea to let people enter dates without forcing the format yourself)....

 

<?php

if(!preg_match('/[0-3][0-9]\/[0-1][0-9]\/2[0][0-9][0-9]/', $date) Errors('date'); //Assuming you wrote an Errors() function.
  else echo 'Email is formatted correctly';

?>

[cpd]

Yer thats exactly the sort of thing i wanted, would you mind explainign it coz i dont fully understand it!

[.josh]

Well, your question wasn't very specific. What exactly are you checking? User input? A record stored in a database? A string?

 

 

Anyway...assuming it's a string or something manually entered in a form (Bad idea to let people enter dates without forcing the format yourself)....

 

<?php

if(!preg_match('/[0-3][0-9]\/[0-1][0-9]\/2[0][0-9][0-9]/', $date) Errors('date'); //Assuming you wrote an Errors() function.
  else echo 'Email is formatted correctly';

?>

 

Not so fast there buddy. That regex would validate 39/19/2099.  Correct format but obviously a bunk date.  And what if this was some kind of birthday date form? Not everybody was born in the year 2000+

[cpd]

So how do you do it the proper way then?

[.josh]

The best way to do it is use dropdown menus for mm dd yyyy  and validate each one with a condition, like check if month is between 1 and 12, etc... and just concatonate them together into your own formatted string.

[cpd]

There would be no point in a vaidation then because they would only be able to use those values. Ok then no worries i think iw ill use Drop downs in that case because i can get it exactly how i want it

[.josh]

There would be no point in a vaidation then because they would only be able to use those values. Ok then no worries i think iw ill use Drop downs in that case because i can get it exactly how i want it

 

Always always ALWAYS validate input.

[cpd]

MEGA LOL

[DarkWater]

MEGA LOL

 

I hope you're not "MEGA LOL"-ing at his word of warning, because you can easily edit dropdown menus and send WHATEVER you want to a script if you have half a brain.

[.josh]

No, seriously.  Consider this simple form:

 

<form action='somepage.php' method = 'post'>
   <select name = 'blah'>
      <option value = '1'>1</option>
      <option value = '2'>2</option>
      <option value = '3'>3</option>
   </select>
   <input type = 'submit' value = 'submit'>
</form>

 

If you do not check to see if $_POST['blah'] is 1,2 or 3.  I can do:

 

Rightclick

view source

highlight and copy form

paste into my own html file

change one of the values to anything I want

change the action= from somepage.php to http://www.yoursite.com/somepage.php

save

load up my file in my browser

choose the selection with my altered data

submit

 

Your form takes it without validating, and you get wtfpwned. 

[cpd]

:S:S Oh crap, i didnt realise you could do that. Ouch. Well thats no problemo because i can just check the format of it

 

Or make a quick function to check the format etc!

[cpd]

So how do i check if its from say 1-12 or the the Month is not from Jan to Dec

[.josh]

you would use a condition, like an if statement or something.  That's pretty basic stuff.  There are lots of tutorials out there for php basics.

[cpd]

yer but i dont wana write an if statement say if($VAUE != 1 || $VALUE != 2 etc etc

 

That would take ages

[sasa]

try

<?php
$test = '29/02/2001';
$test = explode('/', $test);
$comp = explode('/',date('d/m/Y',mktime(1,1,1,$test[1],$test[0],$test[2])));
if($test[0]==$comp[0] and $test[1]==$comp[1] and $test[2]==$comp[2]) echo 'OK'; else echo 'no';
?>

[cpd]

Could you explain what mktime does and how it works because i dont understand the php.net explanation

[PFMaBiSmAd]

To test if a date is valid - http://us3.php.net/checkdate

 

yer but i dont wana write an if statement say if($VAUE != 1 || $VALUE != 2 etc etc

If you need to test that a value is or is not in a range of values, there are more ways to do a comparison besides == and !=

http://us.php.net/manual/en/language.operators.comparison.php

 

[.josh]

// example number
$x = 10;

// example 1
if (($x >= 1) && ($x <= 100)) {
  echo "$x is between 1 and 100...and I didn't have to write 100 comparisons!";
}

// example 2
if (in_array($x, range(1,100))) {
  echo "$x is between 1 and 100...and I didn't have to write 100 comparisons!";
}

 

you would use a condition, like an if statement or something.  That's pretty basic stuff.  There are lots of tutorials out there for php basics.