When coding with isset i am getting an fatal error.I have searched stackoverflow but results are not satisfactory.
I am getting
Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead)
My codes are
if (!isset( $size || $color )) {
$style = '';
}else{
$style = 'font-size : ' . $size . ';color:' . $color;
}
As mentioned in the comments (and the error message), you cannot pass the result of an expression to isset.
You can use multiple isset calls, or reverse the logic of your if/else block and pass multiple parameters to isset, which i think is the cleanest solution:
//true if both are set
if(isset($size, $color)) {
$style = 'font-size : ' . $size . ';color:' . $color;
}else{
$style = '';
}
You can clean this up a little further by setting the default value first, thus avoiding the need for an else section:
$style = '';
if(isset($size, $color)) {
$style = 'font-size : ' . $size . ';color:' . $color;
}
You could even use a ternary, though some people find them harder to read:
$style = isset($size, $color) ? 'font-size : ' . $size . ';color:' . $color : '';
you should use this way
if (!isset( $size ) || !isset( $color )) {
Your expression always return either true or false => In theory isset always return true so PHP not allow this
Change
if (!isset( $size || $color )) {
To
if (!isset($size) || !isset($color)) {
Related
I need create a function that checks a parsed value to see if it matches a few other values and then return that match. For example I am trying to match video urls correctly. So if it's youtube do this or if it's vimeo do this or if it's nothing do this. I know how to create a function but I'm not sure what to use for the parse, would it be parse_url?
For my test cases I need to send in the right parameter and then see that the returned values are matching what I want them to be.
Here's what I've tried so far:
function get_video_embed_string($videostring) {
$video_url_parse = parse_url( $videostring, PHP_URL_HOST ); //get the input string ready to parse
$returnstring = ""; //default return string to empty string
if ($video_url_parse === 'vimeo.com') {
$returnstring = str_replace( 'vimeo.com', 'player.vimeo.com', $video_url_parse );
} else if ($video_url_parse === 'youtube.com') {
$returnstring = str_replace( 'youtube.com', 'youtube.com/embed/', $video_url_parse );
} else {
//do nothing
}
return $returnstring;
}
parse_str($returnstring);
//now setup your test cases and see what echos out of the above method
if ($returnstring === 'player.vimeo.com') {
echo "vimeo: <" . get_video_embed_string ("https://vimeo.com/abcdefg123") . ">";
} else if ($returnstring === 'youtube.com/embed/'){
echo "youtube: <" . get_video_embed_string ("https://youtube.com/abcdefg123") . ">";
} else if($returnstring === '' ){
echo "nothing: <" . get_video_embed_string ("https://abc123.com/abcdefg123") . ">";
} else {
echo "empty:< " . get_video_embed_string ("") . ">";
}
I think you're on the right track using parse_url, but I have a couple suggestions for improvement:
instead of the run-on if/elseif chain, use a switch
the str_replace isn't working well as is because you're replacing the parsed host, so why spend the overhead searching again for the string to replace when you've already found it.
in the user comments for parse_url, there's an excellent example to reconstruct the parsed url. this will avoid string replacements where the host name is also part of the url (www.youtube.com/youtubevideo123)
simplify your test cases by just calling your function for each case instead of another if/else chain check.
function get_video_embed_string($videostring) {
$video_url_parse = parse_url($videostring); //get the input string ready to parse
switch ($video_url_parse['host']) {
case 'vimeo.com':
$video_url_parse['host'] = 'player.vimeo.com';
return unparse_url($video_url_parse);
case 'youtube.com':
$video_url_parse['host'] = 'youtube.com/embed';
return unparse_url($video_url_parse);
default:
return unparse_url($video_url_parse);
}
}
function unparse_url($parsed_url) {
$scheme = isset($parsed_url['scheme']) ? $parsed_url['scheme'] . '://' : '';
$host = isset($parsed_url['host']) ? $parsed_url['host'] : '';
$port = isset($parsed_url['port']) ? ':' . $parsed_url['port'] : '';
$user = isset($parsed_url['user']) ? $parsed_url['user'] : '';
$pass = isset($parsed_url['pass']) ? ':' . $parsed_url['pass'] : '';
$pass = ($user || $pass) ? "$pass#" : '';
$path = isset($parsed_url['path']) ? $parsed_url['path'] : '';
$query = isset($parsed_url['query']) ? '?' . $parsed_url['query'] : '';
$fragment = isset($parsed_url['fragment']) ? '#' . $parsed_url['fragment'] : '';
return "$scheme$user$pass$host$port$path$query$fragment";
}
//now setup your test cases and see what echos out of the above method
echo "vimeo: <" . get_video_embed_string ("https://vimeo.com/abcdefg123") . ">\n";
echo "youtube: <" . get_video_embed_string ("https://youtube.com/abcdefg123") . ">\n";
echo "nothing: <" . get_video_embed_string ("https://abc123.com/abcdefg123") . ">\n";
echo "empty:< " . get_video_embed_string ("") . ">\n";
This will result in the following output in source:
vimeo: <https://player.vimeo.com/abcdefg123>
youtube: <https://youtube.com/embed/abcdefg123>
nothing: <https://abc123.com/abcdefg123>
empty:< >
parse_url() is very good for parsing URLs and - in your case - extract the host name from it.
Your example is a little messed up. $returnstring is not defined outside of your function. You should turn error reporting on, so you will see NOTICE messages on this kind of errors.
I assume, your function should return the video embed url, not only the host name. So you should do your replace on $videostring, not $video_url_parse:
function get_video_embed_string($videostring) {
$video_url_parse = parse_url( $videostring, PHP_URL_HOST ); //get the input string ready to parse
$returnstring = ""; //default return string to empty string
if ($video_url_parse === 'vimeo.com') {
$returnstring = str_replace( 'vimeo.com', 'player.vimeo.com', $videostring );
} else if ($video_url_parse === 'youtube.com') {
$returnstring = str_replace( 'youtube.com', 'youtube.com/embed', $videostring );
} else {
//do nothing
}
return $returnstring;
}
This will give you this output:
echo get_video_embed_string("https://vimeo.com/abcdefg123"); // https://player.vimeo.com/abcdefg123
echo get_video_embed_string("https://youtube.com/abcdefg123"); // https://youtube.com/embed/abcdefg123
echo get_video_embed_string("https://abc123.com/abcdefg123"); // <empty string>
[For a more robust approach, I would probably try to extract the video ID from all known valid URL schemes using regexp and just insert this ID in the embed url.]
Basically, I've been trying to make a simple Wordpress widget that displays a QR code with the URL of the current page. I'm using a modififed version of the simple text widget that parses PHP too.
function the_qrcode($permalink = '', $title = '') {
if($permalink && $title == '') {
$permalink = 'http://eternityofgamers.com/forums';
$title = 'Forums';
}
echo '<img src="http://api.qrserver.com/v1/create-qr-code/?data=' .$permalink. '" alt="QR: ' .$title. '"/>;
}
Can someone tell me what's wrong with this? I get a 500 error when I add it to functions.php.
You will need to use the urlencode() function. Generally as a rule of thumb all querystring values should be url encoded.
function the_qrcode( $permalink = '' ) {
if($permalink == '') {
$permalink = 'http://eternityofgamers.com/forums';
}
echo '<img src="http://api.qrserver.com/v1/create-qr-code/?data='.urlencode($permalink);
}
Now you can create your QR code with:
the_qrcode(the_permalink());
Also, you had a very bad missing equals sign. It is very important to understand the difference between = and ==. If you don't, no matter the context = and == mean two different things. = assigns the right hand side to the left. == returns true or false whether the left and right hand side are loosely equal (loosely because casting will be used if the sides are not of the same type).
Look at this example (Codepad demo):
$a = 5;
$b = 10;
if($a = 6) {
echo "This always appears because when you assign a truthy (all non-zero numbers are true) to a variable, true is returned.\n";
echo "Also a should now equal six instead of five: " . $a . "\n";
}
if($b == 10) {
echo "This will work as expected because == is a comparison not an assignment.\n";
echo "And b should still be 10: " . $b;
}
Try with:
<?php
function the_permalink( $permalink ) {
if ($permalink == '') {
echo '<img src="http://api.qrserver.com/v1/create-qr-code/?data=http://eternityofgamers.com/forums" alt="QR Code">';
} else {
echo '<img src="http://api.qrserver.com/v1/create-qr-code/?data='.$permalink;
}
}
?>
(I've corrected a bunch of syntax errors)
I'm using the jquery address plugin to build an ajax driven site, and i've got it working! Yay! For the purposes of this question we can use the test site:
http://www.asual.com/jquery/address/samples/crawling
http://www.asual.com/download/jquery/address
(I had to remove two calls to urlencode() to make the crawling example work.)
I'm encountering a problem with the $crawling->nav() call. It basically uses js and php to load parts of an xml file into the dom. I (mostly) understand how it works, and I would like to modify the example code to include sub pages.
For example, I would like to show 'subnav-project.html' at '/!#/project' and '/!#/project/blue', but not at '/!#/contact'. To do this, I figure php should 'know' what page the user is on, that way I can base my logic off of that.
Is this crazy? Can php ever know the current state of the site if I'm building it this way? If not, how does one selectively load html snippets, or modify what links are shown in navigation menus?
I've never gotten too crazy with ajax before, so any feedback at all would be helpful.
EDIT
This is the crawling class.
class Crawling {
const fragment = '_escaped_fragment_';
function Crawling(){
// Initializes the fragment value
$fragment = (!isset($_REQUEST[self::fragment]) || $_REQUEST[self::fragment] == '') ? '/' : $_REQUEST[self::fragment];
// Parses parameters if any
$this->parameters = array();
$arr = explode('?', $fragment);
if (count($arr) > 1) {
parse_str($arr[1], $this->parameters);
}
// Adds support for both /name and /?page=name
if (isset($this->parameters['page'])) {
$this->page = '/?page=' . $this->parameters['page'];
} else {
$this->page = $arr[0];
}
// Loads the data file
$this->doc = new DOMDocument();
$this->doc->load('data.xml');
$this->xp = new DOMXPath($this->doc);
$this->nodes = $this->xp->query('/data/page');
$this->node = $this->xp->query('/data/page[#href="' . $this->page . '"]')->item(0);
if (!isset($this->node)) {
header("HTTP/1.0 404 Not Found");
}
}
function base() {
$arr = explode('?', $_SERVER['REQUEST_URI']);
return $arr[0] != '/' ? preg_replace('/\/$/', '', $arr[0]) : $arr[0];
}
function title() {
if (isset($this->node)) {
$title = $this->node->getAttribute('title');
} else {
$title = 'Page not found';
}
echo($title);
}
function nav() {
$str = '';
// Prepares the navigation links
foreach ($this->nodes as $node) {
$href = $node->getAttribute('href');
$title = $node->getAttribute('title');
$str .= '<li><a href="' . $this->base() . ($href == '/' ? '' : '?' . self::fragment . '=' .html_entity_decode($href)) . '"'
. ($this->page == $href ? ' class="selected"' : '') . '>'
. $title . '</a></li>';
}
echo($str);
}
function content() {
$str = '';
// Prepares the content with support for a simple "More..." link
if (isset($this->node)) {
foreach ($this->node->childNodes as $node) {
if (!isset($this->parameters['more']) && $node->nodeType == XML_COMMENT_NODE && $node->nodeValue == ' page break ') {
$str .= '<p><a href="' . $this->page .
(count($this->parameters) == 0 ? '?' : '&') . 'more=true' . '">More...</a></p>';
break;
} else {
$str .= $this->doc->saveXML($node);
}
}
} else {
$str .= '<p>Page not found.</p>';
}
echo(preg_replace_callback('/href="(\/[^"]+|\/)"/', array(get_class($this), 'callback'), $str));
}
private function callback($m) {
return 'href="' . ($m[1] == '/' ? $this->base() : ($this->base() . '?' . self::fragment . '=' .$m[1])) . '"';
}
}
$crawling = new Crawling();
You won't be able to make server-side decisions using the fragment-identifier (i.e., everything to the right of the # character). This is because browsers don't send fragment-identifiers to the server. If you're going to want to make server-side decisions, you'll need to use some JavaScript assistance (including AJAX) to communicate what the current fragment-identifier is.
I have a database table that stores various type of operators and values that make expressions like
if(mydBVal1 mydBExpression mydBval2)
{
// do something....!
}
Here is my code thats shows and example of what I want to say and the help I require
e.g:
$data['myValue'] = 100;
$data['operator'] = "<";
$data['comparison_value'] = 150
if( $data['myValue'] . $data['operator'] . $data['comparison_value'] )
{
///do something......
}
I want that if condition to be read as if(100 < 150){}, but the if condition expression is not working properly!
any one here know how I can make it work?
I think you want to use the eval() function.
Be very careful about sanitising the data from the database before evaling it though as you could allow users to execute PHP code that you don't want them to.
$data['myValue']=100;
$data['operator']="<";
$data['comparison_value']= 150;
$eval = sprintf("return(%d %s %d);", $data['myValue'], $data['operator'], $data['comparison_value']);
if(eval($eval))
{
Also you can take a look into php assert
php.net/assert
<?php
var_dump(assert("1 == 1"));
var_dump(assert("1 === null"));
?>
Sample code I used related to my project:
$assert_statement =
(($typecriteria != 'IS_NULL' || $typecriteria != 'NOT_NULL' ) ? "'".$value."'" : '' )
. " " . $typecriteria . " '" . $criteriavalue."'";
// Active assert and make it quiet
assert_options(ASSERT_ACTIVE, 1);
assert_options(ASSERT_WARNING, 0);
assert_options(ASSERT_BAIL, 0);
assert_options(ASSERT_QUIET_EVAL, 1);
if ( $debug >= 1 ) {
print __METHOD__." assert debug ".$assert_statement."<br>";
var_dump(assert( $assert_statement ));
}
if (assert( $assert_statement ) === true )
{
return true;
}
Here is my If Else Statement
if(isset($row['content']) && strlen($row['content'])) {
$content = $row['content'];
}
elseif(isset($row['description']) && strlen($row['description'])) {
$content = $row['description'];
}
I tried to create a condition using ternerary operator and ended for with a error: Here is my ternerary condition
$content = isset($row['content']) && strlen($row['content']) ? $row['content'] : isset($row['description']) && strlen($row['description']) ? $row['description'] : '';
What is the correct statement?
You're making your code very very unreadable by changing your condition into a ternary operator. Anyhoo, the following works without an error.
$content = (isset($row['content']) && strlen($row['content']))
? $row['content']
: (isset($row['description']) && strlen($row['description'])
? $row['description']
: '');
Wrapped the last expression in parenthesis so PHP doesn't try to evaluate it separately.
Try putting inside bracket the first term of ?: and the last term of first ?:.
$content = (isset($row['content']) && strlen($row['content'])) ? $row['content'] : ((isset($row['description']) && strlen($row['description'])) ? $row['description'] : '');