1.PHP Basics (25 Questions)
Q1. What is PHP and how does it work?
PHP (Hypertext Preprocessor) is a server-side scripting language designed for web development. When a user requests a PHP page, the server processes the PHP code using its built-in module, generates HTML, and sends that HTML back to the user’s browser. The user never sees the actual PHP source code.
Q2. How do you define a variable in PHP?
Variables in PHP start with a $ sign, followed by the name of the variable. They are case-sensitive and must start with a letter or an underscore.
PHP
$websiteName = “CodeXRush”;
Q3. How do you define a constant in PHP?
You can define a constant using the define() function or the const keyword. Constants cannot be changed once they are set and do not use a $ sign.
define(“SITE_URL”, “https://codexrush.com”);
Q4. What are the different data types supported by PHP?
PHP supports several data types: String, Integer, Float (Double), Boolean, Array, Object, NULL, and Resource.
Q5. What is the difference between single quotes and double quotes in PHP strings?
Single quotes treat the content as a literal string, while double quotes allow for “variable interpolation,” meaning PHP will replace variable names with their actual values inside the string.
$name = “User”;
echo ‘Hello $name’; // Outputs: Hello $name
echo “Hello $name”; // Outputs: Hello User
Q6. What is the difference between echo and print?
echo has no return value and can take multiple parameters. print has a return value of 1, so it can be used in expressions, but it is slightly slower than echo.
Q7. What are “magic constants” in PHP?
These are predefined constants that change depending on where they are used. Examples include __LINE__ (current line number), __FILE__ (full path of the file), and __DIR__ (directory of the file).
Q8. Explain the use of the var_dump() function.
var_dump() is used to display structured information about one or more variables, including their type and value. It is highly useful for debugging.
Example: $a = 32;
echo var_dump($a);
// Output: int(32)
Q9. How do you concatenate two strings in PHP?
You use the dot (.) operator to join two strings together.
$first = “Codex”;
$second = “Rush”;
echo $first . $second;
// Outputs: CodexRush
Q10. What is the difference between == and ===?
== (Equal) checks if the values are the same after type juggling. === (Identical) checks if the values are the same and of the same data type.
Q11. What is the purpose of the php.ini file?
The php.ini file is the default configuration file for PHP. It controls settings like file upload limits, error reporting and memory limits.
Q12. How do you write comments in PHP?
You can use // or # for single-line comments and /* … */ for multi-line comments.
Q13. What is the ternary operator in PHP?
It is a shorthand for the if-else statement. It uses a question mark and a colon.
$status = ($age >= 18) ? “Adult” : “Minor”;
Q14. Explain the Null Coalescing Operator (??).
It returns its first operand if it exists and is not NULL; otherwise, it returns the second operand. It is useful for checking if a variable is set.
$username = $_GET[‘user’] ?? ‘Guest’;
Q15. What is the use of gettype()?
It returns the type of a variable as a string (e.g., “integer”, “string”, “boolean”).
Q16. How can you check if a variable is set and not NULL?
You use the isset() function. It returns true if the variable exists and is not null.
Q17. What does empty() check?
empty() checks if a variable is “empty.” A variable is considered empty if it is “” (empty string), 0, 0.0, “0”, NULL, FALSE, or an empty array.
Q18. What is the purpose of the unset() function?
unset() destroys a specified variable, freeing up the memory associated with it.
Q19. How do you declare an array in PHP?
You can use the array() function or the short square bracket syntax [].
$colors = [“Red”, “Green”, “Blue”];
Q20. What is a “heredoc” in PHP?
Heredoc is a way to define multi-line strings without using many quotes. It starts with <<< followed by an identifier.
Q21. What is the difference between static and global variables?
A global variable is accessible everywhere in the script. A static variable exists only inside a function but retains its value even after the function execution finishes.
Q22. How do you find the length of a string?
You use the strlen() function. To find the word count, you use str_word_count().
Q23. What is type juggling in PHP?
PHP is a loosely typed language, meaning it automatically converts variables to the required data type depending on the context of the operation.
Q24. How do you define a multi-line string in PHP?
You can simply hit enter inside double quotes or use the Heredoc/Nowdoc syntax.
Q25. What is the use of the is_numeric() function?
It checks whether a variable is a number or a numeric string. It returns true if it is, false otherwise.
