User input filtering

crazygol4 · #1 29-Aug-2008, 17:16

Okay so I've got a form where users input basic information (name, username, password, address, etc) and I want to filter it to make sure users aren't inserting code, including whitespace, using incorrect chars, etc.

If anyone has the script to do all of this already, I would love to have it, but I have planned to build it myself. This may be an ongoing post as theres many aspects to filtering user input. BUT, my immediate question is how do I count whitespace ONLY (no text)....

This is the code that I'm using (that isn't working):

PHP Code:


$text = "The  quick brown fox";
$textcount = preg_replace('/\s\s+\s-/', '', $text, $count);
echo $count;

Thanks in advance for help,
crazygol4

crazygol4 · #2 30-Aug-2008, 10:16

Okay I've got a fix for it:

PHP Code:


$text = "The quick brown fox";
echo "<br>";
echo $text;
echo "<br>";
echo strlen($text);
echo "<br>";
$textfix = str_replace(' ', '', $text);
echo strlen($textfix);
$iswhitespace = strlen($text) - strlen($textfix);
echo "<br>";
echo $textfix;
echo "<br>";
echo $iswhitespace;

So that code has some test features in it, the below code will do all the work without displaying, and will redirect to a different page if the string contains whitespace.

PHP Code:


$text = $_POST[yourvar];
$textfix = str_replace(' ', '', $text);
$iswhitespace = strlen($text) - strlen($textfix);
if ($iswhitespace > 0) {
    header( "Location: sendthemtoadiffpage.php");
    exit;
}

Hope this is helpful!
-crazygol4

Howard_L · #3 02-Sep-2008, 09:54

Looks like you could get a yes or no answer in one line by using: strpos( string, find [, start] )

PHP Code:


#  some command line examples:
$  php -a
Interactive mode enabled

<?php
$s1 = "stringwithnospaces";
$s2 = "string with space";
$s3 = "string with two  spaces together";

echo strpos($s1, " ");
          # <-Note: nothing returned, (as pos 0 would indicate the first character).
echo strpos($s2, " ");
6
echo strpos($s3, "  ");
15
##########
if( strpos($s1, " ") )
  echo "yes";
else
  echo "no";
no
##########
if( strpos($s2, " ") )
  echo "yes";
else
  echo "no";
yes

Here is a reference for all the string functions: w3schools.com/php/php_ref_string.asp

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User input filtering

Re: User input filtering

Re: User input filtering