How to avoid having "whitespace" posts in a site? - php

Question

I have this site : http://aasiskos.webpages.auth.gr/1905_YPA/Rating.php . I log in ( user = mpa#mpa.com and pass = 123a ) and then I can add a comment by pushing the green image. I am trying to put a restriction to the "post comment" thing. I want to avoid having comments posted with whitespace (no text). But it doesn't work. The posts that are not whitespace , are not shown either. The problem is under the last "else" thing in the code below. How can i change that ?
$link=mysql_connect('localhost', 'student1905','123456');
mysql_select_db('student1905');
$title= $_POST["title"];
$text= $_POST["text"];
if (!$link) {
die('Could not connect: ' . mysql_error());
}
else {
header("Location:Rating.php");
}
if ( ($_POST[title]=" ") || ($_POST[text]=" ") ) {
header("Location:Rating.php");
}
else
{
$sql = "INSERT INTO kritikes (Auxon, Date, Title, Text) VALUE ('',CURDATE(),'$_POST[title]', '$_POST[text]')";
mysql_query($sql);
}
?>

Answer 1

You can use PHP's trim() function to remove white space from the beginning and end of a string. This would easily allow you to evaluate the content.
However, there are several other problems with your code. Firstly, you are redirecting to Rating.php if your database connection exists. This will prevent any future code in the PHP from running.
You're also using a deprecated family of functions. mysql_* bring serious security implications to the table. You should really consider using MySQLi or PDO. Along with this, your code is open to SQL injections, so you should certainly make sure that you sanitize your inputs.
That having been said, the following code should work for you, but you'll need to make the changes based on my recommendations above regarding mysql_* and SQL injection:
$link = mysql_connect('localhost', 'student1905','123456');
mysql_select_db('student1905');
$title= trim($_POST["title"]);
$text = trim($_POST["text"]);
if(!$link)
{
die('Could not connect: ' . mysql_error());
}
else {
if(strlen($title) == 0 || strlen($text) == 0)
{
header("Location:Rating.php");
}
else
{
$sql = "INSERT INTO kritikes (Auxon, Date, Title, Text) VALUE ('',CURDATE(),'$title', '$text')";
mysql_query($sql);
}
}

Answer 2

you can use trim() to take out any leading and trailing white space. examples:
trim(' h i '); //is equal to "h i"
trim('hello world'); //is equal to "hello world"
it does not remove the middle whitespace.
You can use empty to check if the string is empty regardless how many whitespace it contains. Examples:
empty(""); //returns true
empty(" "); //returns true
empty(" a"); //returns false

Answer 3

Use trim to remove any leading or trailing whitespace. Then check if the message is empty (ie. strlen($message) === 0).

Answer 4

You can do like this-
if(trim($_POST[title])=="") {
// your code
}

Answer 5

For just spaces, use str_replace: For ex, $string = str_replace(' ',
'', $string);
For all whitespace, use preg_replace:
$string = preg_replace('/\s+/', '', $string);
If you just are dealing with excess whitespace on the beginning or
end of the string you can use trim(), ltrim() orrtrim() to remove
that.

Answer 6

Read in your post variables into actual variables, trimming while doing so. Then, do a check to make sure neither of them is an empty string. If neither is empty, then proceed to do your sql query. See example below.
$title = trim($_POST['title']);
$text = trim($_POST['text']);
if($title != '' && $text != '') {
$sql = "INSERT INTO kritikes (Auxon, Date, Title, Text) VALUE ('',CURDATE(),'$title', '$text')";
mysql_query($sql);
}

Answer 7

try updating this line :
if ( ($_POST[title]=" ") || ($_POST[text]=" ") )
to :
if ( strlen(trim($_POST[title]))== 0 || strlen(trim($_POST[text]))== 0 )