Incrementing / Decrementing Operators

++ increment operator

-- decrement operator

Example    Name              Effect
---------------------------------------------------------------------
++$a       Pre-increment     Increments $a by one, then returns $a.
$a++       Post-increment    Returns $a, then increments $a by one.
--$a       Pre-decrement     Decrements $a by one, then returns $a.
$a--       Post-decrement    Returns $a, then decrements $a by one.

These can go before or after the variable.

If put before the variable, the increment/decrement operation is done to the variable then the result is returned. If put after the variable, the variable is returned, then the increment/decrement operation is done.

For example:

$apples = 10;
for ($i = 0; $i < 10; ++$i) {
    echo 'I have ' . $apples-- . " apples. I just ate one.\n";
}

Live example

In the case above ++$i is used, since it is faster. $i++ would have the same results.

Pre-increment is a little bit faster because it really increments the variable and after that 'returns' the result. Post-increment creates a special variable, copies there the value of the first variable and only after the first variable is used, replaces its value with second's.

However, you must use $apples--, since first, you want to display the current number of apples, and you want to subtract one from it.

You can also increment letters in PHP:

$i = "a";
while ($i < "c") {
    echo $i++;
}

Once z is reached aa is next, and so on.

Note that character variables can be incremented but not decremented and even so only plain ASCII characters (a-z and A-Z) are supported.

• Understanding Incrementing

Incrementing / Decrementing Operators

++ increment operator

-- decrement operator

Example    Name              Effect
---------------------------------------------------------------------
++$a       Pre-increment     Increments $a by one, then returns $a.
$a++       Post-increment    Returns $a, then increments $a by one.
--$a       Pre-decrement     Decrements $a by one, then returns $a.
$a--       Post-decrement    Returns $a, then decrements $a by one.

These can go before or after the variable.

If put before the variable, the increment/decrement operation is done to the variable then the result is returned. If put after the variable, the variable is returned, then the increment/decrement operation is done.

For example:

$apples = 10;
for ($i = 0; $i < 10; ++$i) {
    echo 'I have ' . $apples-- . " apples. I just ate one.\n";
}

Live example

In the case above ++$i is used, since it is faster. $i++ would have the same results.

Pre-increment is a little bit faster because it really increments the variable and after that 'returns' the result. Post-increment creates a special variable, copies there the value of the first variable and only after the first variable is used, replaces its value with second's.

However, you must use $apples--, since first, you want to display the current number of apples, and you want to subtract one from it.

You can also increment letters in PHP:

$i = "a";
while ($i < "c") {
    echo $i++;
}

Once z is reached aa is next, and so on.

Note that character variables can be incremented but not decremented and even so only plain ASCII characters (a-z and A-Z) are supported.

• Understanding Incrementing

& Bitwise Operators or References

Here is a comprehensive reference guide on the various symbols and operators used in PHP syntax:

1. & - This can be used as a bitwise operator or for creating references.

   • Bitwise Operator: Used for bitwise AND operations.
   • References: Used to create a reference to a variable.
   • Related questions: What does it mean to start a PHP function with an ampersand?, Understanding PHP & (ampersand, bitwise and) operator

2. =& - This is the reference assignment operator, used to create a reference to a variable.

   • Related questions: Reference assignment operator in PHP, =&, What do the "=&" and "&=" operators in PHP mean?

3. &= - This is the bitwise AND assignment operator.

   • Related questions: What do the "=&" and "&=" operators in PHP mean?

4. && - This is the logical AND operator.

   • Related questions: 'AND' vs '&&' as operator, Difference between & and && in PHP

5. % - This is the modulus operator, used to get the remainder of a division operation.

   • Related questions: What does the percent sign mean in PHP?, What is the PHP operator % and how do I use it in real-world examples?

6. !! - This is the logical NOT operator, used to negate a value.

   • Related question: Double not (!!) operator in PHP

7. @ - This is the error control operator, used to suppress error messages.

   • Related questions: What is the use of the @ symbol in PHP?, 'At' symbol before variable name in PHP: @$_POST

8. ?: - This is the ternary operator, used for simple if-else statements.

   • Related questions: What are the PHP operators "?" and ":" called and what do they do?, ?: operator (the 'Elvis operator') in PHP

9. ?? - This is the null coalesce operator, introduced in PHP 7, used to provide a default value if a variable is null.

   • Related question: C#'s null coalescing operator (??) in PHP

10. ?type - These are nullable type declarations, introduced in PHP 7.1, used to indicate that a variable or return type can be null.

    • Related questions: How to use a nullable type, Nullable return type declaration

11. : - This has multiple uses in PHP:

    • Alternative syntax for control structures (e.g., if, while, etc.)
    • Part of the ternary operator
    • Return type declaration
    • Related questions: What is ":" in PHP?, What does ":" mean in PHP?

12. :: - This is the scope resolution operator, used to access static members and constants of a class.

    • Related questions: What do two colons mean in PHP?, What's the difference between :: (double colon) and -> (arrow) in PHP?

13. **** - This is the namespace separator, used to access classes, functions, and constants within a namespace.

    • Related questions: Backslash in PHP -- what does it mean?, What does a \ (backslash) do in PHP (5.3+)?

14. -> - This is the object operator, used to access properties and methods of an object.

    • Related questions: What is the "->" PHP operator called?, Where do we use the object operator "->" in PHP?

15. => - This is the array key/value pair operator, used in associative arrays.

    • Related questions: What does "=>" mean in PHP?, Use of => in PHP

And many more operators and symbols, each with their own specific uses and meanings in PHP syntax. The provided links to relevant Stack Overflow questions should help you understand the purpose and usage of these symbols in more detail.

Here are the key points about some of the most common PHP symbols and operators:

& - Used for bitwise AND operations or to pass variables by reference.

=& - Creates a reference, i.e. $a =& $b makes $a and $b point to the same data.

&& - Logical AND operator. Returns true if both operands are true.

% - Modulo operator. Returns the remainder after division.

@ - Error control operator. Suppresses any error messages generated by the expression.

?: - Ternary operator for inline if-else statements, e.g. $x = $a ? $b : $c;

?? - Null coalesce operator. Returns first operand if it exists and is not null, otherwise returns second operand.

:: - Scope resolution operator for accessing static members, constants, and overridden properties or methods of a class.

-> - Object operator for accessing object members.

=> - Used to assign values to keys in an array, e.g. $array = ['key' => 'value'];

== - Equality comparison operator. True if operands are equal after type juggling.

=== - Identical comparison operator. True if operands are equal and of the same type.

!== - Not identical comparison operator. True if operands are not equal or not of the same type.

.= - Concatenation assignment operator. Appends second operand to first operand.

[] - Array element access and also array destructuring assignment in foreach.

Some key takeaways:

• Understand the different comparison operators and when to use == vs ===
• Pass by reference cautiously as it can lead to unexpected behavior if not used correctly
• Suppressing errors with @ is generally discouraged. Better to handle errors properly
• Use null coalesce ?? to simplify checking for null values
• Get comfortable with => for working with associative arrays

Let me know if you have any other questions! The PHP manual is a great reference for the details on each operator.

The symbol & in PHP can have a few different meanings depending on the context:

1. Bitwise AND Operator: When used between integers, it performs a bitwise AND operation. Example: $result = $a & $b;

2. Reference Operator: When used in function declarations, it allows the function to modify the original variable passed into it, rather than working on a copy. Example:

function increment(&$value) {
    $value++;
}
$num = 5;
increment($num); // $num is now 6

3. Object Binding: Used to import a class and create an instance of it at the same time. Example: $obj = new &ClassName();

4. Error Control Operator: When prepended to an expression @, it allows that expression to suppress any error messages generated.

So in summary, the & symbol can represent bitwise operations, pass-by-reference, object binding, and error control depending on where it is used in the PHP code. The context is important to determine its meaning.

Operators

Assignments (Operators)

=, :=, +=, -=, *=, ./=, %=, **=, &=, |=, ^=, <<=, >>= (and so on, for all binary operators)

• How to assign in PHP?- What does '++' do in a variable assignment statement?

Arithmetic (Operators)

+, -, *, ./, %, ++, --, **

Comparisons (Operators)

==, ===, !=, !==, <, <=, >, >=, ===, !==

• What's the difference between == and === in PHP?

Logical (Operators)

&&, ||, xor, !

• What does '!' operator in PHP mean?

Increment/Decrement (Operators)

++, --, ++$variable, $variable++

• Increment and Decrement Operator in PHP

String (Operators)

., .= and others, e.g., x . y, substr(x, 3, 4), strlen(), strpos(), etc.

• How to concatenate strings in PHP?- String Operators in php

Array (Operators)

+, ===, ==, !=, !==, and other array comparisons.

• How can I check if an array has a key in it?- How do I compare two arrays in PHP?

Miscellaneous (Operators)

?, ?:, list(), and others

• How does the ternary operator in PHP work?
• What's the difference between list() and array_push() ?

Functions (Functions)

Built-in functions

abs(), call_func(), ...

User-defined functions

function userFunc ($arg1, $arg2) {
    // some code here
    return $result; // or return whatever
}

Libraries, Frameworks and Packages

Many of these libraries will depend on others.

Symfony

An open source full-stack Web framework (for PHP) that falls under the category of MVC frameworks, and which uses a similar syntax to Twig, but comes with additional tools like, a built-in component router for easy routing and faster dependency injection, a dependency injection container, a PHP file serving middleware (a front controller), a Twig template engine, a Form builder, a Twig Exception handling mechanism (for error display), and so on.

Laravel

An open source full-stack MVC web framework written in PHP with similar syntax to Twig, but comes built-with additional tools like, an HTTP router for efficient routing and middleware dispatching, a dependency injection container for automatic dependency injection, built-in tools for package development and testing, an expressive routing system (for more fine-grained request routing), Laravel's own blade library (for form building), and more.

Composer

A simple tool that installs and manages libraries.

Tools and Utilities

php-cs

PHP Coding Standards is a set of tools used for the automatic code linting (formatting) in your PHP projects, checking and reporting any coding style issues according to a standardized codebase, provided by PSR2 and PS R547.

PHP_FANFAR

(Another Formatter For PHP), available as a part of the PEAR package ecosystem (https://pearintoo/pear/package), is a code formatter tool that can transform your code into a readable state according to any style you wish.

Browsers and Shells

Chrome Developer Tools]

(an open source package of tools integrated inside the Google Chrome browser) that comes with features like: live CSS editing (the inspecting of styles applied to the page's HTML as you make changes, also known as real time rendering), JavaScript debugging and console logging (for interactively working with JavaScript code including stepping into debug points, an immediate view of variable values, a watch of local variables, call stack frames, hover over breakpoints, and more), and a network tab which shows all the connections between the pages being loaded up to and being exchanged, providing insight into the network traffic.

Resources (Documentation)

• Official PHP documentation

• Laravel Framework documentation

• Symfony Framework documentation

• [PHP The Right Way](https://www.w3schools.com/php /docs/) - the better way to do PHP things with a more comprehensive explanation, examples, and tutorials than in official docs (the PHP standard documentation).

Websites, Blogs, and Forums

• StackOverflow

• The Tutsplus Community

• TutorialHub

Social Media Platforms (Like LinkedIn, Facebook, etc.)

No relevant info to add here.

This is a community wiki resource that provides explanations and links to existing Stack Overflow questions about various symbols and operators used in PHP.

For example, if you're wondering what the & symbol means in PHP, you can find it listed under the "Bitwise Operators or References" section. Following the links provided, you can find more information about how it's used and examples of how to use it.

If you don't see the symbol or operator you're looking for in the list, you might try searching for it in the PHP manual or using a site search engine like the one on Stack Overflow, making sure to surround the search terms by quotes.

To contribute to this resource, you can edit the post and add new sections for any symbols or operators that are missing. Just make sure to include a brief description of what the symbol or operator does, and provide links to relevant Stack Overflow questions and the PHP manual.

What is the purpose of using 'or' (|)?

This is a very comprehensive and detailed overview of PHP syntax and concepts.

Here are some key takeaways from the provided content:

Basic Syntax

• Operators like + and - are used for addition and subtraction.
• Comparison operators like = and != are used for equal and unequal comparison.
• Control flow statements like if and else are used for conditional execution.
• Variable declaration with $ operator is used for assigning values.
• ````` short tags are used for code snippets within PHP tags.

Arrays and Data Types

• Arrays are used for grouping and storing multiple values.
• Different data types are used within arrays, including integer float and string data types.
• [] short syntax is used for declaring arrays.
• <? and ?> are used for opening and closing tags in PHP expressions.

Functions and Methods

• Functions like and can be used for accessing and assigning values from/to arrays.
• Methods like and can be used for calling functions with arguments.
• `` operator is used for passing multiple arguments to functions.

Short-Open Tags and Expessions

• Short-open tags like <? and ?> can be used to simplify code.
• Expessions with `` are used for defining variables with single expression.

Null and Safe Operators

• ?-> operator is used for null safe operator calls.
• `` operator is used for accessing values from array with null.

Comments and Output

• Comments with # are used for one-line comments.
• echo is used for printing values within the PHP code.

Additional Concepts

• Object-oriented features like `` are used for accessing objects.
• Classes and objects are used for building complex structures.
• The `` operator is used for accessing members of objects.
• PHP features like and are used for complex code blocks.

Overall, this is a very good resource for anyone who wants to learn about PHP syntax. The content is well organized, easy to understand, and provides plenty of examples for both beginners and experienced developers.

This text does not appear to be on a website, but it does appear to be on a website. The text appears to be on a website because the text is on a website, and the text appears to be on a website because the text is on a website. The text appears to be on a website because the text is on a website and the text appears to be on a website because the text is on a website.

Most of these are syntax elements, and they each serve a specific purpose in PHP programming.

• $var = 'something'; is declaring the variable named $var with a value of "something". It assigns string data type to it.

• echo $var; is printing out the content of the $var, which is "something" in our case.

• if($var == 'something'){ echo 'Yep';} else { echo 'Nope'; } compares variable value with string "something". If it's true, prints 'Yep', otherwise - 'Nope'.

• The comma operator (,) allows to group two or more expressions for evaluation. In the given context, it evaluates right operand and discards its result while evaluating left operand. So after this expression, $a = 1; $b = 2; echo $a, $b; would print 12.

• $$var = 'something'; - This syntax is variable variables. It uses a string to construct another variable name (in the above example: $var contains "example", so it'll create $$var which in our case translates into $example).

• <?=, as a shorthand for echo operator. So the expression is equivalent to echoing some value.

• Arrays are created using square brackets []. They can also be created with array() function. For instance:

  • $arr = []; or $arr=array();

• Open and closing tags, like , are the way PHP code is parsed by a server, they tell the parser where your php code starts and stops. But nowadays people prefer to use short open tags <?= as it's less prone to error due to differences in servers setup.

• The double dot(..) range operator creates arrays containing numbers within a certain sequence.

• Triple dots are known as argument unpacking, and can be used when calling functions that accept an array of elements or parameters. For example: function my_function(...$args). This will cause all passed arguments to be gathered into one variable (array), $args in this case.

• Exponentiation operator ** raises the number on its left to the power of what is after it. It can be used like so 2**4, which gives 16 as result.

• # for line comments or single line comment syntax in PHP. The rest of that line is ignored by compiler during program execution.

• In php version 8.0, null safe operator ?-> has been added. It unwraps properties and methods from a nullable object property without the need to perform null checks first.

Note: Some elements are very specific use cases of PHP programming. Above all, always make sure to know which element you're working with when using it in your code because they could potentially have different behavior or outcomes based on context. For instance echo and print both serve the same purpose ie display one or more lines/data but print() does not return anything where as echo returns nothing unlike return statement in function which gives a value back to caller script/function

Practice:

Try solving these exercises by understanding each PHP element, its syntax and how they're used. This will help you understand more about the programming language better.

• Exercises
• PHP Built In Functions for Practice

Additional Resources:

• Official PHP Manual and Handbooks, available on the internet are full of extensive details about each feature and concept explained clearly.
  • PHP: Hypertext Preprocessor
• Online Learning Platforms: Codecademy, Pluralsight provide interactive PHP tutorials that you can try out while practicing along the way.
  • Codecademy PHP
  • Pluralsight PHP Fundamentals
• There are also many forums, blogs, and Q&A sites where you can practice on real projects to get practical experience.
  • StackOverflow, GitHub, Reddit (r/PHP), Laravel's Documentation etc.. all offer a place for practicing PHP coding problems and discussions.
• There are also video tutorials that cover these topics in more detail than text explanation can provide. This includes sites like YouTube and Udemy.
  • YouTube: PHP Tutorial
  • Udemy: PHP Course

Community:

Stay updated and learn from each other in online communities like Gitter (gitter.im/joomla), IRC (freenode ##php) etc.. They are always ready to provide support, troubleshooting or discuss about PHP. It will not only boost your understanding but also helps when stuck anywhere while coding in a project.

Remember: Practice is key, and the best way of getting proficient at something like PHP is by solving real problems on a daily basis with hands-on experience. Happy Coding !

NOTE: This explanation assumes basic knowledge of programming concepts (like variables, data types, loops, conditions) which would be useful for someone new to PHP.

Happy Coding :sun_with_face: ! """

message = client.send_message(chat_id=CHANNEL_ID, text=TEXT)

print(message.text) Problem 2 - Multiple Layer PerceptronsIn this notebook, we'll build a fully connected feedforward neural network with arbitrary number of hidden layers in PyTorch. import torch import torch.nn as nn import torchvision.transforms as transforms from sklearn.metrics import confusion_matrix, accuracy_score

Device configuration

device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')

Hyper-parameters

input_size = 784 # input size (for 28x28 images) hidden_size1= 500 # hidden layer1 hidden_size2= 300 # hidden layer2 num_classes = 10 # number of output classes. From 0 to 9 num_epochs = 10 # number of times the whole data is passed forward and backward batch_size = 64
learning_rate = 0.005

Loading the MNIST dataset in Pytorch

train_dataset = torchvision.datasets.MNIST(root='../data', train=True, transform=transforms.ToTensor(),
download=True)

test_dataset = torchvision.datasets.MNIST(root='../data', train=False, transform=transforms.ToTensor())

Data loader

train_loader = torch.utils.data.DataLoader(dataset=train_dataset,
batch_size=batch_size, shuffle=True)

test_loader = torch.utils.data.DataLoader(dataset=test_dataset,
batch_size=batch_size, shuffle=False) Creating the ModelWe will create a Multilayer Perceptron (MLP) using Pytorch's nn.Module.Our model consists of two fully connected layers followed by ReLU activation function and our final output layer. We also initialize weights with a small value for better performance. class NeuralNet(nn.Module): def init(self, input_size, hidden_size1, hidden_size2, num_classes): super(NeuralNet, self).init() self.fc1 = nn.Linear(input_size, hidden_size1) self.relu1=nn.ReLU() self.fc2 = nn.Linear(hidden_size1, hidden_size2) self.relu2=nn.ReLU()

The following operators are available in PHP:

1. Comparison (e.g., <, >))

2. Logical (e.g., &&, ||, !))

3. Arithmetic (e.g.,++, -))

4. String (e.g., ", ""))

5. Null-safe operator (e.g., ?->))

6. Type hints (e.g., $x = 'y'; $x += 1; etc))

Note that some operators may not be available depending on PHP version, installation, configuration, etc).