But, as discussed, isset($data) will also return false if $data was set, but was set to null.
#Php for loop in html to hide info code
The author of this code presumably wanted to check if keyShouldBeSet was set in $data. do something here if 'keyShouldBeSet' is not set This behavior is more problematic than it might appear at first and is a common source of problems.Ĭonsider the following: $data = fetchRecordFromStorage($storage, $identifier) This is the technical support forum for Toolset - a suite of plugins for developing WordPress sites without writing PHP. Unset($value) // $value no longer references $arrĬommon Mistake #2: Misunderstanding isset() behaviorĭespite its name, isset() not only returns false if an item does not exist, but also returns false for null values. To still get the benefit of using references in foreach loops without running the risk of these kinds of problems, call unset() on the variable, immediately after the foreach loop, to remove the reference e.g.: $arr = array(1, 2, 3, 4) Pass 3: Copies $array (which now equals “2”) into $value (which is a reference to $array), so $array still equals 2.Pass 2: Copies $array (i.e., “2”) into $value (which is a reference to $array), so $array now equals 2.Pass 1: Copies $array (i.e., “1”) into $value (which is a reference to $array), so $array now equals 1.
As a result, here’s what happens during each step of the second foreach loop: Specifically, since $value is now being accessed by value (i.e., by copy), foreach copies each sequential $array element into $value in each step of the loop. The last value on the last line is indeed a 2, not a 3.Īfter going through the first foreach loop, $array remains unchanged but, as explained above, $value is left as a dangling reference to the last element in $array (since that foreach loop accessed $value by reference).Īs a result, when we go through the second foreach loop, “weird stuff” appears to happen. The above code will output the following: 1,2,3
JSExLoop.html -> .Here’s an example of the kind of evasive and confusing bugs that this can lead to: $array = įoreach ($array as &$value) // by value (i.e., copy) binary data, typed arrays, new collections (maps, sets and WeakMap), promises. After the loop completes, therefore, $value still points to the last element of $array and remains in scope. On each iteration foreach sets the reference to point to the next element of $array. Thus, $value in the above example is a reference within the top scope of the script. The main thing to remember is that foreach does not create a scope. In other words, if the timeout is the default 30 seconds, and 25 seconds into script. Subsequent operations involving $value could therefore unintentionally end up modifying the last element in the array. When called, settimelimit() restarts the timeout counter from zero. Specifically, in the above example, after the code is executed, $value will remain in scope and will hold a reference to the last element in the array. The problem is that, if you’re not careful, this can also have some undesirable side effects and consequences.
#Php for loop in html to hide info how to
Not sure how to use foreach loops in PHP? Using references in foreach loops can be useful if you want to operate on each element in the array that you are iterating over. Common Mistake #1: Leaving dangling array references after foreach loops When the hidden attribute in HTML sets to true, the element is hidden, or when the value is false, the element is visible. This article highlights ten of the more common mistakes that PHP developers need to beware of. But its ease of use notwithstanding, PHP has evolved into quite a sophisticated language with many frameworks, nuances, and subtleties that can bite developers, leading to hours of hair-pulling debugging. By setting exposephp to off in your php.ini file, you reduce the amount of information available to them. Without this javascript, the PHP loop works perfectly, but all the information is displayed.PHP makes it relatively easy to build a web-based system, which is much of the reason for its popularity. A few simple techniques can help to hide PHP, possibly slowing down an attacker who is attempting to discover weaknesses in your system. I have a javascript show/hide function, which will only show the jobsheets when the project link is clicked. I have a PHP loop region, which repeats all completed projects for each customer, then displays all jobsheets linked to those projects.
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