The above code will output the following: 1,2,3 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) 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.

Subsequent operations involving $value could therefore unintentionally end up modifying the last element in the array. 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. 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 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. PHP makes it relatively easy to build a web-based system, which is much of the reason for its popularity.

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