Foreach PHP: the last element

There are two interesting possibilities in PHP arrays: the foreach motion and the last element. That is, in the forward and reverse directions. A language gives every variable the right to change its type at its discretion, and the array element is also a variable.

If we take into account that there is a pointer to the active element in the array and can be controlled as you like, then if the developer oversights, the program won’t count the wonders, and its behavior will be “independent”.

foreach php

PHP Massive Features

Arrays have always been a popular concept in programming, and recently they have acquired a new meaning and syntactic forms. The PHP foreach cycle and the concept of the “last element” are equivalent in some sense, and differ only in the direction of movement:

  • foreach ();
  • array_pop ().

In both cases, you can create arrays, as it turns out, but you can always see everything. Both cases open up the possibility to put their own semantics into the PHP syntax.

In the first case, the cycle officially looks at all the elements in the order of their appearance in the array or in the order that has developed after manipulating it.In the second case, the process is the same, but occurs from the tail of the array to its beginning.

If a problem occurs, PHP declares an element error. If not an array is used as a parameter, in the first case we have a PHP message: warning invalid argument for foreach, in the second - an error of the E_WARNING level, that is, “nothing terrible, but problems will come later”.

foreach php arrays

O order in arrays

The appearance of associative arrays marked a banal change in attitudes towards them. If the programmer does not control the situation, problems cannot be avoided.

Many tasks or parts of the algorithm prescribe to create ordered arrays and then the keys always go in order.

When it is possible to delete an element, and the keys that follow it do not move forward, the array is not much different from the associative one. Is that the developer did not have a hand in how to call this or that element of the array.

The usual iteration over the elements in a for () loop is interesting and makes sense when the keys go sequentially. Each array always has a key in order. When an element is deleted, an empty space is formed and there will be an error in the for () loop.

When searching through an array using foreach () or array_pop (), there will never be problems, but only in the first case the array will remain, in the second it will disappear.

php warning invalid argument supplied for foreach

About the provided syntax

The foreach loop in PHP has a familiar form.You can specify the search as is: ($ aPass as $ cLine), or you can specify the key: ($ aPass as $ cKey => $ cLine).

Loop through array_pop ($ aPass) - from the field of stack impromptu past, although relevant and interesting in the present. This is not a loop at all, but simply the output of the last element of the array, in which it is removed from the array.

When the PHP foreach statement starts, the internal array pointer is always set to its first element. Changing the pointer inside the loop can lead to miracles.

It is important that the $ cLine variable does not indicate the element of the $ aPass array, but contains its value, so if you need to change the element of the array, you must put the & character in front of it. In this case, $ cLine will be a reference to the element of the array, not its value.

Errors foreach, php last element = ok!

The author's example is not a picture.

What mistake is more valuable: fatal or skipped is like seasoning, to the taste of the developer, taking into account the adequate response of the customer. If an item has been removed from an array, then only the for loop will notice. The PHP foreach loop and PHP array_pop are absolutely loyal here.

If the element is of the wrong type, it will be noticeable in the same way as in the main body of the program.

If the foreach parameter does not include an array or an object, there will be an Invalid argument ..., although the variant with array_pop is usually unreal. But when this does happen, nothing will happen except NULL.

Arrays and objects

PHP provides the ability to treat objects as arrays. What is the point of this difficult to say, but this is available. Arrays can contain values ​​of any type and change it during program execution. Naturally, an array element can be another array or object. The nesting level is limited by common sense.

Operators and language constructs have nothing to do with recursion or nesting level. This is a serious lag in the syntax of control structures from the syntax of data description. Developers are used to such phenomena as PHP arrays, foreach, array_pop, so it’s convenient to work with them.

The prospects that control structures will change (even in the distant future) are not yet foreseen.

foreach php last element

Object arrays (start)

We must pay tribute to the fact that the appearance of a pair of foreach / array_pop was not long in coming, but this is only half the story. By and large, the for () {}, while () {} and do {} while () loops, it's time to take proper control of the voids in the arrays and solve the recursion problem when the element is an array.

However, the consciousness of the developer still remembers the unshakable doctrine: an array is a set of elements, where an array element is another entity that needs to be processed accordingly.

The problem here is not to be resolved in the foreseeable future, even taking into account the growth rate of information technology development. Owing to what it is necessary to be content with what is.

Simplest arrays (inset)

The most primitive case is when the elements of an array are numbers, strings, other elements of constant composition and designation.

foreach loop in php

For example, digits of binary system of calculation. Similarly:

  • octal;
  • decimal;
  • hexadecimal.

To say that the simplest will be an array of months, but only under certain conditions, since in most cases you will need a digital representation of the month, a three-letter, Russian, Chinese, full or some other.

Definitely the simplest will be an array of letters of the alphabet. In the simplest array, you can define everything that is usually called constants and invariably for the problem being solved.

Object arrays (continued)

If you give up any other options for the type of element, in addition to the object and the simplest array, then everything will turn out absolutely wonderful even in the hands of modern control structures of the language, which have retained their essence from ancient times.

It is known that an object combines data and methods, memory and action.The general practice of object-oriented programming, understood by many, is a kind of abstract object that has nothing, but everything is only planned.

foreach php

A wonderful state of affairs, developing a chain of heirs from an abstract object, we get the opportunity to form arrays of the same type of data - abstract objects. What exactly they will be in each specific case is a matter of technique and, having shifted the care of implementing semantics into the hands of each concrete descendant according to its essence, we get what we want.

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