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a simple php syntax question.

Answer 1

+1 A:

See this:

http://stackoverflow.com/questions/1276909/php-syntax-question-what-does-the-question-mark-and-colon-mean-closed

It is the ternary operator in PHP as well as other languages.

Bob Fincheimer 2010-07-30 12:01:54

Answer 2

+1 A:

$country = empty($_POST['country']) ? die ("ERROR: Enter a country") :

I suppose this script accepts data from a form sent by POST method. If country variable is empty, exit the script with error message.

mysql_escape_string($_POST['country']);

This function should return escaped value from given variable. Therefore it should be written like this

$country = mysql_escape_string($_POST['country']);

More info here: http://php.net/manual/en/function.mysql-escape-string.php

dwich 2010-07-30 12:02:59

Answer 3

+3 A:

It is called ternary operator and is simply shorthand of this code:

if (empty($_POST['country']))
{
  die ("ERROR: Enter a country");
}
else
{
  $country = mysql_escape_string($_POST['country']);
}

Syntax:

condition ? used if true : used if false;

Or you can do assignments:

variable = condition ? used if true : used if false;

More Info:

http://www.tuxradar.com/practicalphp/3/12/4

Sarfraz 2010-07-30 12:03:32

thank you i was expecting an answer like this, i am not used to shorthand.. thank you for this reply.. :)

Ibrahim Azhar Armar 2010-07-30 12:05:04

Good answer, +1, but you forgot to add `$country = ` to the `else` block

Igor Zinov'yev 2010-07-30 12:05:07

@Igor Zinov'yevL Yes forgot to add that, thanks :)

Sarfraz 2010-07-30 12:06:47

For more information, here's the syntax of the ternary operator : condition ? value if true : value if false

Elenaher 2010-07-30 12:07:06

Hi there,in the else condidtion i want to echo something like a link to go back to index page, i tried using concatenation and it is not happening.. check the last string$user = empty($_POST['user']) ? die("Error : Please enter username") : mysql_escape_string($_POST['user']) . echo "$_SERVER['PHP_SELF']";how do i achieve this??

Ibrahim Azhar Armar 2010-07-30 13:25:41

First off, in this case you would be better off with a full if/else statement, this whole thing is totally unreadable. And the problem here, I think, is that concatenation operator has a higher precedence. So you need to do it this way: `$condition ? ($if_true) : ($if_false . $concatenated_string);`

Igor Zinov'yev 2010-07-30 15:38:15

@Ibrahim Azhar Armar: To redirect to index page use `header("location: index.php");`

Sarfraz 2010-07-31 13:24:58

Answer 4

+1 A:

$country = empty($_POST['country']) ?
           die ("ERROR: Enter a country") :
           mysql_escape_string($_POST['country']);

If the expression empty($_POST['country']) evaluates to true, then die ("ERROR: Enter a country") will be evaluated (and the result would be assigned to $country, but for the fact that die() halts script execution).

On the other hand, if empty($_POST['country']) evaluates to false, then mysql_escape_string($_POST['country']) will be evaluated, and the result will be assigned to $country.

Hammerite 2010-07-30 12:04:56

Hi there,in the else condidtion i want to echo something like a link to go back to index page, i tried using concatenation and it is not happening.. check the last string$user = empty($_POST['user']) ? die("Error : Please enter username") : mysql_escape_string($_POST['user']) . echo "$_SERVER['PHP_SELF']"; how do i achieve this??

Ibrahim Azhar Armar 2010-07-30 13:27:35

I'm not sure what you want to achieve. If you use `$user = empty($_POST['user']) ? die("Error : Please enter username") : mysql_escape_string($_POST['user']).$_SERVER['PHP_SELF'];` then assuming the call to `empty()` returns false, `$User` will be `mysql_escape_string($_POST['user'])` concatenated with `$_SERVER['PHP_SELF']`. If you actually want to `echo` something conditionally, perhaps it would be best for you to go with an `if ... else` approach.

Hammerite 2010-07-31 00:31:01

Answer 5

+1 A:

It's test condition: if variable from HTML FORM is empty then print out "ERROR: Enter a country", else set variable country safe characters..

HWTech 2010-07-30 12:05:30

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