I Made a PIN authentication on my website, and I don't want my user using common PINs like 12345, 11111, 121212, etc.
I tried this
if($PIN=="111111" || $PIN="222222"){
echo "This PIN is common";
}
But I think that Will be too long for a simple function?
How to simplify it?
Your problem is actually quite simple, you want, for example, to avoid pins that have multiples iterations of a same character in a row OR/AND avoid pins that have a same character repeated more than X times in a string.
Using Regex we can easily achieve something like this: For example, the following will return 1 if 3 characters or more are in a row.
<?php
$pin = '111025';
if ( preg_match( '/(.)\1{2}/', $pin ) ) {
return true;
} else {
return false;
}; ?>
Learn more
RegEx.
A regular expression is a sequence of characters that forms a search
pattern. When you search for data in a text, you can use this search
pattern to describe what you are searching for.
Function
Description
preg_match()
Returns 1 if the pattern was found in the string and 0 if not
( )
You can use parentheses ( ) to apply quantifiers to entire patterns. They also can be used to select parts of the pattern to be used as a match
.
Find just one instance of any character
n{x}
Matches any string that contains a sequence of X n's
PHP RegEx # https://www.w3schools.com/php/php_regex.asp
Related
I want to be able to effectively match a string with a number of regular expressions to determine what this string represents.
^[0-9]{1}$ if string matches it is of type 1
^[a-x]{300}$ if string matches it is of type 2
... ...
Iterating over a collection containing all of the regular expressions every time I want to match a string is way too heavy for me.
Is there any more effective way? Maybe I can compile these regexps into one big one? Maybe something that works like Google Suggestions, analysing letter after letter?
In my project, I am using PHP/MySQL, however I will be thankful for a clue in any language.
Edit:
Operation of matching a string will be very frequent and string values will vary.
What you could do, if possible, is grouping your regexes together and determine in which group a string belongs.
For instance, if a string doesn't match \d, you know there is no digit in it and you can skip all regexes that require one. So (for instance) instead of matching against +300 regexes, you can narrow that down to just 25.
You can sum up your regexes like this:
^([0-9])|([a-x]{300})$
Later, if you get more regex, you can do this:
^([0-9])|([a-x]{300})|([x-z]{1,5})|([ab]{2,})$...
Then use this code:
$input=...
preg_match_all('#^([0-9])|([a-x]{300})$#', $input, $matches);
foreach ($matches as $val) {
if (isset($val[1])) {
// type 1
} else if (isset($val[2])) {
// type 2
}
// and so on...
}
Since the regexes are going to be changing, I don't think you can get a generic answer - both your regex(es), and the way you handle them will need to evolve. For now, if you're looking to optimize the processing of your script, test for known strings before evaluating using something like indedOf to lighten the regex load.
For instance, if you have 4 strings:
asdfsdfkjslkdujflkj2lkjsdlkf2lkja
100010010100111010100101001001011
101032021309420940389579873987113
asdfkajhslkdjhflkjshdlfkjhalksjdf
Each belongs to a different "type" as you've described it, so you could do:
//type 1 only contains 0 or 1
//type 2 must have a "2"
//type 3 contains only letters
var arr = [
"asdfsdfkjslkdujflkj2lkjsdlkf2lkja",
"100010010100111010100101001001011",
"101032021309420940389579873987113",
"asdfkajhslkdjhflkjshdlfkjhalksjdf"
];
for (s in arr)
{
if (arr[s].indexOf('2') > 0)
{
//type 2
}
else if (arr[s].indexOf('0') > 0)
{
if ((/^[01]+$/g).test(arr[s]))
//type 1
else
//ignore
}
else if ((/^[a-z]+$/gi).test(arr[s]))
//type 3
}
See it in action here: http://jsfiddle.net/remus/44MdX/
I am looking to develop a search function that allows users to just search for the item, or modify their search with a price range in brackets. So that is to say if they are looking for a car, then they can enter either car and receive all cars in the database or they can enter car (100, 299) or car(100, 299) and receive only cars in the database with the price range of 100 to 299.
Before what I did was three different explode function calls, but that was cumbersome and looked ridiculously ugly. I also tried to put the the brackets in an array and then compare that against the word searched (a word is basically an array of characters) but that didn't work. Finally I have been reading up on strpos and substr but they don't seem to fit the requirements as strpos returns the first occurrence of the the character and substr returns the characters within a specified length after a specific occurrence.
So for example the problem with strpos is the user can just enter ( and no ) bracket and I'll make a call to my search function with who knows what. And for example the problem with substr is that the price range can vary wildly.
You can use preg_match to parse the search string - I'm assuming that's the part you're having issues with.
if (preg_match('/car ?\(([^,]+), ?([^\)]+)\)/', $search_text, $matches)) {
$low_price = $matches[1];
$high_price = $matches[2];
//do your price filtering here
}
The regular expression may need a little tweaking, I don't remember offhand if parentheses need to be escaped in character classes.
Yes, Sam is right. You should do this with regular expressions.
Look for preg_match() on the documentation
To complete his answer, the regular expression for your case is:
$regex = "^([a-zA-Z]+)\s\(([0-9]+),([0-9]+)\)$"
if (preg_match($regex, $search_text, $matches)) {
$type = $matches[0];
$low_price = $matches[1];
$high_price = $matches[2];
//do your price filtering here
}
Be careful, as the array containing matches starts at index 0, not one.
A user enters a password, say 'tomorrow1234'. I'm aware that I can split it into an array with str_split, but after that, I want to go through each value and search them for things such as capitalization, number, or white space.
How would I go about doing this?
This is an old standby function I use to valiate password complexity. It requires that the password contains upper and lowercase letters, as well as non-alpha characters. Length checks are trivial and are handled elsewhere.
$req_regex = array(
'/[A-Z]/', //uppercase
'/[a-z]/', //lowercase
'/[^A-Za-z]/' //non-alpha
);
foreach($req_regex as $regex) {
if( !preg_match($regex, $password) ) {
return NULL;
}
}
I use the array and a loop so it's easy to add/remove conditions if necessary.
Sounds like your trying to verify password strength.
Check out this web page, your solution would be pretty complex to write a specific answer for, but you can use regex to check for things like capitalization, symbols and digits. This page has several examples you could modify for your needs.
http://www.cafewebmaster.com/check-password-strength-safety-php-and-regex
This is what I would use:
(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$
Checks for 1 letter, 1 number, 1 special character and at least 8 characters long.
I'm trying to check if a string has a certain number of occurrence of a character.
Example:
$string = '123~456~789~000';
I want to verify if this string has exactly 3 instances of the character ~.
Is that possible using regular expressions?
Yes
/^[^~]*~[^~]*~[^~]*~[^~]*$/
Explanation:
^ ... $ means the whole string in many regex dialects
[^~]* a string of zero or more non-tilde characters
~ a tilde character
The string can have as many non-tilde characters as necessary, appearing anywhere in the string, but must have exactly three tildes, no more and no less.
As single character is technically a substring, and the task is to count the number of its occurences, I suppose the most efficient approach lies in using a special PHP function - substr_count:
$string = '123~456~789~000';
if (substr_count($string, '~') === 3) {
// string is valid
}
Obviously, this approach won't work if you need to count the number of pattern matches (for example, while you can count the number of '0' in your string with substr_count, you better use preg_match_all to count digits).
Yet for this specific question it should be faster overall, as substr_count is optimized for one specific goal - count substrings - when preg_match_all is more on the universal side. )
I believe this should work for a variable number of characters:
^(?:[^~]*~[^~]*){3}$
The advantage here is that you just replace 3 with however many you want to check.
To make it more efficient, it can be written as
^[^~]*(?:~[^~]*){3}$
This is what you are looking for:
EDIT based on comment below:
<?php
$string = '123~456~789~000';
$total = preg_match_all('/~/', $string);
echo $total; // Shows 3
I have a PHP array of strings. The strings are supposed to represent PIN codes which are of 6 digits like:
560095
Having a space after the first 3 digits is also considered valid e.g. 560 095.
Not all array elements are valid. I want to filter out all invalid PIN codes.
Yes you can make use of regex for this.
PHP has a function called preg_grep to which you pass your regular expression and it returns a new array with entries from the input array that match the pattern.
$new_array = preg_grep('/^\d{3} ?\d{3}$/',$array);
Explanation of the regex:
^ - Start anchor
\d{3} - 3 digits. Same as [0-9][0-9][0-9]
? - optional space (there is a space before ?)
If you want to allow any number of any whitespace between the groups
you can use \s* instead
\d{3} - 3 digits
$ - End anchor
Yes, you can use a regular expression to make sure there are 6 digits with or without a space.
A neat tool for playing with regular expressions is RegExr... here's what RegEx I came up with:
^[0-9]{3}\s?[0-9]{3}$
It matches the beginning of the string ^, then any three numbers [0-9]{3} followed by an optional space \s? followed by another three numbers [0-9]{3}, followed by the end of the string $.
Passing the array into the PHP function preg_grep along with the Regex will return a new array with only matching indeces.
If you just want to iterate over the valid responses (loop over them), you could always use a RegexIterator:
$regex = '/^\d{3}\s?\d{3}$/';
$it = new RegexIterator(new ArrayIterator($array), $regex);
foreach ($it as $valid) {
//Only matching items will be looped over, non-matching will be skipped
}
It has the benefit of not copying the entire array (it computes the next one when you want it). So it's much more memory efficient than doing something with preg_grep for large arrays. But it also will be slower if you iterate multiple times (but for a single iteration it should be faster due to the memory usage).
If you want to get an array of the valid PIN codes, use codaddict's answer.
You could also, at the same time as filtering only valid PINs, remove the optional space character so that all PINs become 6 digits by using preg_filter:
$new_array = preg_filter('/^(\d{3}) ?(\d{3})$/D', '$1$2', $array);
The best answer might depend on your situation, but if you wanted to do a simple and low cost check first...
$item = str_replace( " ", "", $var );
if ( strlen( $item ) !== 6 ){
echo 'fail early';
}
Following that, you could equally go on and do some type checking - as long as valid numbers did not start with a 0 in which case is might be more difficult.
If you don't fail early, then go on with the regex solutions already posted.