1. The difference between Iterator and foreach is the polymorphic difference (the bottom layer of foreach is Iterator) Iterator is an interface type, it does not care about the type of collection or array; both for and foreach need to know the type of collection first, even the type of elements in the collection; 1. Why is it said that the bottom layer of foreach is the code written by Iterator: Decompiled code: 2. The difference between remove in foreach and iterator. First, look at the Alibaba Java Development Manual, but no error will be reported in case 1, and an error will be reported in case 2 (java. util.ConcurrentModificationException) first

?The steps for PHP to determine the number of the foreach loop: 1. Create an array of "$fruits"; 2. Create a counter variable "$counter" with an initial value of 0; 3. Use "foreach" to loop through the array, and Increase the value of the counter variable in the loop body, and then output each element and their index; 4. Output the value of the counter variable outside the "foreach" loop to confirm which element the loop reaches.

This article will explain in detail how PHP returns an array after key value flipping. The editor thinks it is quite practical, so I share it with you as a reference. I hope you can gain something after reading this article. PHP Key Value Flip Array Key value flip is an operation on an array that swaps the keys and values ??in the array to generate a new array with the original key as the value and the original value as the key. Implementation method In PHP, you can perform key-value flipping of an array through the following methods: array_flip() function: The array_flip() function is specially used for key-value flipping operations. It receives an array as argument and returns a new array with the keys and values ??swapped. $original_array=[

The explode function in PHP is a function used to split a string into an array. It is very common and flexible. In the process of using the explode function, we often encounter some errors and problems. This article will introduce the basic usage of the explode function and provide some methods to solve the error reports. 1. Basic usage of the explode function In PHP, the basic syntax of the explode function is as follows: explode(string$separator,string$stri

Title: Common errors and solutions when using the explode function in PHP In PHP, the explode function is a common function used to split a string into an array. However, some common errors can occur due to improper use or incorrect data format. This article will analyze the problems you may encounter when using the explode function, and provide solutions and specific code examples. Mistake 1: The delimiter parameter is not passed in. When using the explode function, one of the most common mistakes is that the delimiter parameter is not passed in.

Difference: 1. for loops through each data element through the index, while forEach loops through the data elements of the array through the JS underlying program; 2. for can terminate the execution of the loop through the break keyword, but forEach cannot; 3. for can control the execution of the loop by controlling the value of the loop variable, but forEach cannot; 4. for can call loop variables outside the loop, but forEach cannot call loop variables outside the loop; 5. The execution efficiency of for is higher than forEach.

This article will explain in detail about the current element in the array returned by PHP. The editor thinks it is very practical, so I share it with you as a reference. I hope you can gain something after reading this article. Get the current element in a PHP array PHP provides a variety of methods for accessing and manipulating arrays, including getting the current element in an array. The following introduces several commonly used techniques: 1. current() function The current() function returns the element currently pointed to by the internal pointer of the array. The pointer initially points to the first element of the array. Use the following syntax: $currentElement=current($array);2.key() function key() function returns the array internal pointer currently pointing to the element

Use the PHP function "explode" to split a string into an array. In PHP development, you often encounter situations where you need to split a string according to the specified delimiter. At this time, we can use PHP's built-in function "explode" to convert string to array. This article will introduce how to use the "explode" function to split a string and give relevant code examples. The basic syntax of the "explode" function is as follows: arrayexplode(