You've been tasked with improving the security of an existing web application. Upon review, you notice that the application doesn't validate or sanitize user input before processing. Which potential vulnerabilities could this introduce?
- SQL Injection, Cross-Site Scripting (XSS), Command Injection, and more
- Better User Experience, Improved Performance, Data Integrity
- Enhanced Scalability, Improved Caching, Reduced Latency
- No Significant Impact on Security
Failing to validate and sanitize user input can introduce serious vulnerabilities like SQL Injection, XSS, Command Injection, and more. It can compromise the application's data, security, and integrity. The other options may bring some benefits, but the security risks outweigh them.
Which of the following PHP functions is used to check if a given key or index exists in an array?
- key_exists
- in_array
- array_key_exists
- index_exists
To check if a given key or index exists in a PHP array, you should use the array_key_exists function. This function checks if a specific key exists in an array, which is particularly useful for associative arrays.
Consider you are building a search functionality for your website. Which function would you use to determine if a particular keyword exists within a content string?
- strpos()
- str_replace()
- str_word_count()
- str_split()
The strpos() function is used to find the position of a substring (keyword) within a string. It returns the position or false if not found, making it suitable for searching within a content string.
The ________ function in PHP returns an array of files and directories from the specified directory.
- file_get_contents
- dir()
- scandir()
- list_dir()
The scandir() function is used in PHP to return an array of files and directories in a specified directory. It's commonly used for directory listing operations.
In the context of form validation, what does the term "sanitization" refer to?
- Removing malicious code
- Validating user credentials
- Cleaning and formatting data
- Authenticating the user
Sanitization in form validation involves cleaning and formatting user input data to remove harmful or unwanted characters, ensuring it's safe for processing.
Consider a scenario where you're building a CMS and you want to log errors to a specific file. Which PHP functions would be most suitable to open and write to this file?
- fopen() and fwrite()
- readfile() and copy()
- file_get_contents() and file_put_contents()
- file() and fwrite()
To open and write to a specific file in PHP, you should use fopen() to open the file and fwrite() to write to it. These functions offer fine-grained control over file handling, crucial for logging errors.
To ensure an uploaded file is not malicious, one should validate the file's ________ before saving it.
- File extension
- File size
- File name
- MIME type
The correct option is "MIME type." This is crucial because a file's MIME type provides information about its content, allowing you to verify that the uploaded file matches its claimed type and is not malicious.
How can you prevent the inheritance of an exception class in PHP?
- Declare the exception class as 'final'
- Use 'private' inheritance
- Implement 'protected' inheritance
- Use 'static' keyword inheritance
In PHP, you can prevent inheritance of a class by declaring it as 'final.' This ensures that no other class can extend it. Exception classes are often made final to prevent further customization or accidental overriding of their behavior.
What is the significance of the E_ALL constant in PHP error reporting?
- Report all error types
- Ignore all errors
- Log errors to a file
- Display errors on the webpage
The E_ALL constant in PHP error reporting is significant because it represents a bitmask that includes all error types. When used, it tells PHP to report and handle all types of errors in your code.
Once a constant is defined in PHP, can its value be changed later in the script?
- Yes
- No
- Only within functions
- Only within classes
In PHP, once a constant is defined, its value cannot be changed later in the script. Constants are intended to hold values that do not change during the script's execution.