Understanding PHP Variable Declaration

In PHP, variables play an essential role, representing a data storage and providing a named location to our program where the data can be processed. They are essentially containers for storing information. The correct way to declare a PHP variable is a critical knowledge that each developer must-have.

From the question, the correct way to declare a PHP variable is "$val = 10;".

Declaration Syntax

To declare a PHP variable, you start with a dollar sign ($) followed by the name of the variable. Then, an equal sign (=) is used to assign a value to the variable. In this case, 10 is the value being assigned to the variable $val.

$val = 10;

What makes the other options incorrect?

Looking at the other choices, we have val = 10;, $10 = 'val';, and $val;.

1. val = 10; - This is incorrect because PHP variables must start with a dollar sign ($).

2. $10 = 'val'; - In PHP, a variable cannot start with a numeric value. Hence this is an incorrect variable declaration.

3. $val; - This technically isn't incorrect, but it just doesn't assign any value to the variable $val. It's undefined and does not have any value whatsoever.

Practical Use-Cases of PHP Variables

Variables in PHP are commonly used to store data that will be used throughout a script. This could include simple data like numbers and strings, or more complex data types like arrays and objects. Here's an example:

$user_name = "John Doe";
$user_age = 25;

echo "Hello, I am $user_name and I am $user_age years old.";

In the code snippet above, the variables $user_name and $user_age are used to store information about a user, which can be used multiple times within the script.

A Final Note on PHP Variable Naming Conventions

While PHP allows flexibility with variable names (they can contain letters, numbers, and underscores), it's essential to keep a clear and consistent naming convention. A universal guideline is to always begin your variable name with a letter or underscore and avoid using spaces within the variable's name. This not only prevents possible errors but also makes your code more readable and maintainable.

Remember, the key to mastering PHP variable declaration lies in practice and consistent use of correct syntax and naming conventions.