I have a variable like this
$string = "0>0.1";
I want to evaluate this inside an if loop like this
if($string)
{
///something
}
but im getting an error if i am doing this. How to go about it
you do not understand how evaluations or strings work.
If you put anything in a string, it will not be evaluated, but simply contain that value from that moment on.
$string = "0>0.1"; // contains "0>0.1"
$bool = 0>0.1; // contains TRUE
The IF statement needs a boolean, not a string.
You can use eval to evaluate things in strings. Remember that eval is evil and any php code may be in it.
You got some awful advise with your duplicate. Here is a safer eval variant that will actually evaluate to an result:
$str = "0>0.1";
if (preg_replace('/^(\d+\.?\d*)([><])(\d+\.?\d*)$/e', "$1 $2 $3", $str))
{
Note that it would still return true for invalid strings like "1>2b". You would need a match and a separate expression evaluation for that. (Writing a faux mini parser here isn't difficult, but obviously overkill for your question.)
Related
I want to know if we can replace if(preg_match('/boo/', $anything) and preg_match('/poo/', $anything))
with a regex..
$anything = 'I contain both boo and poo!!';
for example..
From what I understand of your question, you're looking for a way to check if BOTH 'poo' and 'boo' exist within a string using only one regex. I can't think of a more elegant way than this;
preg_match('/(boo.*poo)|(poo.*boo)/', $anything);
This is the only way I can think of to ensure both patterns exists within a string disregarding order. Of course, if you knew they were always supposed to be in the same order, that would make it more simple =]
EDIT
After reading through the post linked to by MisterJ in his answer, it would seem that a more simple regex could be;
preg_match('/(?=.*boo)(?=.*poo)/', $anything);
By using a pipe:
if(preg_match('/boo|poo/', $anything))
You can use the logical or as mentioned by #sroes:
if(preg_match('/(boo)|(poo)/,$anything)) the problem there is that you don't know which one matched.
In this one, you will match "I contain boo","I contain poo" and "I contain boo and poo".
If you want to only match "I contain boo and poo", the problem is really harder to figure out Regular Expressions: Is there an AND operator?
and it seems that you will have to stick with the php test.
To take conditions literally
if(preg_match('/[bp]oo.*[bp]oo/', $anything))
You can achieve this by altering your regular expression, as others have pointed out in other answers. However, if you want to use an array instead, so you do not have to list a long regex pattern, then use something like this:
// Default matches to false
$matches = false;
// Set the pattern array
$pattern_array = array('boo','poo');
// Loop through the patterns to match
foreach($pattern_array as $pattern){
// Test if the string is matched
if(preg_match('/'.$pattern.'/', $anything)){
// Set matches to true
$matches = true;
}
}
// Proceed if matches is true
if($matches){
// Do your stuff here
}
Alternatively, if you are only trying to match strings then it would be much more efficient if you were to use strpos like so:
// Default matches to false
$matches = false;
// Set the strings to match
$strings_to_match = array('boo','poo');
foreach($strings_to_match as $string){
if(strpos($anything, $string) !== false)){
// Set matches to true
$matches = true;
}
}
Try to avoid regular expressions where possible as they are a lot less efficient!
I need to be able to check if a variable contains the first part of a string. For example, "foobaz xy". Everything after "foobaz xy" can be ignored for the match. This has to be case insensitive too and there must be a space between foobaz and xy. Is there already a built-in function in PHP which handles this, or is a regular expression required to do this? Last and not the least, if more than one method which has a faster execution time? Thanks!
There is no built-in function for it, but there is a tiny workaround which can achieve the same thing. Check the following example:
$string = "foobaz xyewew";
if (stripos($string, "foobaz xy") === 0) {
echo "It starts with foobaz xy";
}
As for the case insensitive issue, you can copy the new string to another and convert it in all lower case, that would make it case insensitive.
Lets say string A= foobaz xy and b=sth sth sth then all you need to do is to take a substring of string b which will always be the size of foobaz xy, hence, if b is less than foobaz xy in character count, it will be discounted automatically. If not, then you need to compare the substring to the constant string A and that will solve the problem.
see php substring here:
see strcmp here to compare the substring and your string
see here to convert a string into all lowercase
Fastest way to check that:
$variable = "FooBaz xy test string";
$isContain = strpos(strlower($variable, "foobaz xy")) === 0;
The first answer is correct, more info on http://www.php.net/manual/en/function.stripos.php. Always remember that it is a bad practice to use regular expressions in simple string checking.
I'm trying use preg_match in an IF statement and return false if a string contains some templated functions not allowed.
Here are some example templated functions allowed:
{function="nl2br($value.field_30)"}
{function="substr($value.field_30,0,250)"}
{function="addslashes($listing.photo.image_title)"}
{function="urlencode($listing.link)"}
{function="AdZone(1)"}
These are mixed in with html etc.
Now I'd like this preg_match statement to return true if regex matches the code format but didn't contain one of the allowed function keywords:
if (preg_match('(({function=)(.+?)(nl2br|substr|addslashes|urlencode|AdZone)(.+?)\})',$string)) {
// found a function not allowed
} else {
// string contains only allowed functions or doesn't contain functions at all
}
Does anyone know how to do this?
Not quite sure what you're trying here, but if I were to make a regexp that matched a list of words (or function names as the case may be), I'd do somthing like
// add/remove allowed stuff here
$allowed = array( 'nl2br', 'substr', 'addslashes' );
// make the array into a branching pattern
$allowed_pattern = implode('|', $allowed);
// the entire regexp (a little stricter than yours)
$pattern = "/\{function=\"($allowed_pattern)\((.*?)\)\"\}/";
if( preg_match($pattern, $string, $matches) ) {
# string DOES contain an allowed function
# The $matches things is optional, but nice. $matches[1] will be the function name, and
# $matches[2] will be the arguments string. Of course, you could just do a
# preg_replace_callback() on everything instead using the same pattern...
} else {
# No allowed functions found
}
The $allowed array makes it easier to add/remove allowed function names, and the regexp is stricter about the curly brackets, quotes and general syntax, which is probably a good idea.
But first of all, flip the if..else branches, or use a !. preg_match is meant for, well, matching stuff in the string, not for matching stuff that isn't in there. So you can't really get it to return true for something that isn't there
Still, as Álvaro mentioned, regexps probably aren't the best way to go about this, and it is pretty risky to have functions exposed like that, no matter the rest of the code. If you just needed to match words it should work fine, but since it's function calls with arbitrary arguments... well. I can't really recommend it :)
Edit: First time around, I used preg_quote on the imploded string, but that of course just escapes the pipe characters, and then the pattern won't work. So skip preg_quote, but then just be sure that function names don't contain anything that might mess up the final pattern (e.g. run each function name through preg_quote before imploding the array)
I need to read a string, detect a {VAR}, and then do a file_get_contents('VAR.php') in place of {VAR}. The "VAR" can be named anything, like TEST, or CONTACT-FORM, etc. I don't want to know what VAR is -- not to do a hard-coded condition, but to just see an uppercase alphanumeric tag surrounded by curly braces and just do a file_get_contents() to load it.
I know I need to use preg_match and preg_replace, but I'm stumbling through the RegExps on this.
How is this useful? It's useful in hooking WordPress.
Orion above has a right solution, but it's not really necessary to use a callback function in your simple case.
Assuming that the filenames are A-Z + hyphens you can do it in 1 line using PHP's /e flag in the regex:
$str = preg_replace('/{([-A-Z]+)}/e', 'file_get_contents(\'$1.html\')', $str);
This'll replace any instance of {VAR} with the contents of VAR.html. You could prefix a path into the second term if you need to specify a particular directory.
There are the same vague security worries as outlined above, but I can't think of anything specific.
You'll need to do a number of things. I'm assuming you can do the legwork to get the page data you want to preprocess into a string.
First, you'll need the regular expression to match correctly. That should be fairly easy with something like /{\w+}/.
Next you'll need to use all of the flags to preg_match to get the offset location in the page data. This offset will let you divide the string into the before, matching, and after parts of the match.
Once you have the 3 parts, you'll need to run your include, and stick them back together.
Lather, rinse, repeat.
Stop when you find no more variables.
This isn't terribly efficient, and there are probably better ways. You may wish to consider doing a preg_split instead, splitting on /[{}]/. No matter how you slice it you're assuming that you can trust your incoming data, and this will simplify the whole process a lot. To do this, I'd lay out the code like so:
Take your content and split it like so: $parts = preg_split('/[{}]/', $page_string);
Write a recursive function over the parts with the following criteria:
Halt when length of arg is < 3
Else, return a new array composed of
$arg[0] . load_data($arg[1]) . $arg[2]
plus whatever is left in $argv[3...]
Run your function over $parts.
You can do it without regexes (god forbid), something like:
//return true if $str ends with $sub
function endsWith($str,$sub) {
return ( substr( $str, strlen( $str ) - strlen( $sub ) ) === $sub );
}
$theStringWithVars = "blah.php cool.php awesome.php";
$sub = '.php';
$splitStr = split(" ", $theStringWithVars);
for($i=0;$i<count($splitStr);$i++) {
if(endsWith(trim($splitStr[$i]),$sub)) {
//file_get_contents($splitStr[$i]) etc...
}
}
Off the top of my head, you want this:
// load the "template" file
$input = file_get_contents($template_file_name);
// define a callback. Each time the regex matches something, it will call this function.
// whatever this function returns will be inserted as the replacement
function replaceCallback($matches){
// match zero will be the entire match - eg {FOO}.
// match 1 will be just the bits inside the curly braces because of the grouping parens in the regex - eg FOO
// convert it to lowercase and append ".html", so you're loading foo.html
// then return the contents of that file.
// BEWARE. GIANT MASSIVE SECURITY HOLES ABOUND. DO NOT DO THIS
return file_get_contents( strtolower($matches[1]) . ".html" );
};
// run the actual replace method giving it our pattern, the callback, and the input file contents
$output = preg_replace_callback("\{([-A-Z]+)\}", replaceCallback, $input);
// todo: print the output
Now I'll explain the regex
\{([-A-Z]+)\}
The \{ and \} just tell it to match the curly braces. You need the slashes, as { and } are special characters, so they need escaping.
The ( and ) create a grouping. Basically this lets you extract particular parts of the match. I use it in the function above to just match the things inside the braces, without matching the braces themselves. If I didn't do this, then I'd need to strip the { and } out of the match, which would be annoying
The [-A-Z] says "match any uppercase character, or a -
The + after the [-A-Z] means we need to have at least 1 character, but we can have up to any number.
Comparatively speaking, regular expression are expensive. While you may need them to figure out which files to load, you certainly don't need them for doing the replace, and probably shouldn't use regular expressions. After all, you know exactly what you are replacing so why do you need fuzzy search?
Use an associative array and str_replace to do your replacements. str_replace supports arrays for doing multiple substitutions at once. One line substitution, no loops.
For example:
$substitutions = array('{VAR}'=>file_get_contents('VAR.php'),
'{TEST}'=>file_get_contents('TEST.php'),
...
);
$outputContents = str_replace( array_keys($substitutions), $substitutions, $outputContents);
I have an array full of patterns that I need matched. Any way to do that, other than a for() loop? Im trying to do it in the least CPU intensive way, since I will be doing dozens of these every minute.
Real world example is, Im building a link status checker, which will check links to various online video sites, to ensure that the videos are still live. Each domain has several "dead keywords", if these are found in the html of a page, that means the file was deleted. These are stored in the array. I need to match the contents pf the array, against the html output of the page.
First of all, if you literally are only doing dozens every minute, then I wouldn't worry terribly about the performance in this case. These matches are pretty quick, and I don't think you're going to have a performance problem by iterating through your patterns array and calling preg_match separately like this:
$matches = false;
foreach ($pattern_array as $pattern)
{
if (preg_match($pattern, $page))
{
$matches = true;
}
}
You can indeed combine all the patterns into one using the or operator like some people are suggesting, but don't just slap them together with a |. This will break badly if any of your patterns contain the or operator.
I would recommend at least grouping your patterns using parenthesis like:
foreach ($patterns as $pattern)
{
$grouped_patterns[] = "(" . $pattern . ")";
}
$master_pattern = implode($grouped_patterns, "|");
But... I'm not really sure if this ends up being faster. Something has to loop through them, whether it's the preg_match or PHP. If I had to guess I'd guess that individual matches would be close to as fast and easier to read and maintain.
Lastly, if performance is what you're looking for here, I think the most important thing to do is pull out the non regex matches into a simple "string contains" check. I would imagine that some of your checks must be simple string checks like looking to see if "This Site is Closed" is on the page.
So doing this:
foreach ($strings_to_match as $string_to_match)
{
if (strpos($page, $string_to_match) !== false))
{
// etc.
break;
}
}
foreach ($pattern_array as $pattern)
{
if (preg_match($pattern, $page))
{
// etc.
break;
}
}
and avoiding as many preg_match() as possible is probably going to be your best gain. strpos() is a lot faster than preg_match().
// assuming you have something like this
$patterns = array('a','b','\w');
// converts the array into a regex friendly or list
$patterns_flattened = implode('|', $patterns);
if ( preg_match('/'. $patterns_flattened .'/', $string, $matches) )
{
}
// PS: that's off the top of my head, I didn't check it in a code editor
If your patterns don't contain many whitespaces, another option would be to eschew the arrays and use the /x modifier. Now your list of regular expressions would look like this:
$regex = "/
pattern1| # search for occurences of 'pattern1'
pa..ern2| # wildcard search for occurences of 'pa..ern2'
pat[ ]tern| # search for 'pat tern', whitespace is escaped
mypat # Note that the last pattern does NOT have a pipe char
/x";
With the /x modifier, whitespace is completely ignored, except when in a character class or preceded by a backslash. Comments like above are also allowed.
This would avoid the looping through the array.
If you're merely searching for the presence of a string in another string, use strpos as it is faster.
Otherwise, you could just iterate over the array of patterns, calling preg_match each time.
If you have a bunch of patterns, what you can do is concatenate them in a single regular expression and match that. No need for a loop.
What about doing a str_replace() on the HTML you get using your array and then checking if the original HTML is equal to the original? This would be very fast:
$sites = array(
'you_tube' => array('dead', 'moved'),
...
);
foreach ($sites as $site => $deadArray) {
// get $html
if ($html == str_replace($deadArray, '', $html)) {
// video is live
}
}
You can combine all the patterns from the list to single regular expression using implode() php function. Then test your string at once using preg_match() php function.
$patterns = array(
'abc',
'\d+h',
'[abc]{6,8}\-\s*[xyz]{6,8}',
);
$master_pattern = '/(' . implode($patterns, ')|(') . ')/'
if(preg_match($master_pattern, $string_to_check))
{
//do something
}
Of course there could be even less code using implode() inline in "if()" condition instead of $master_pattern variable.