COMP721 Web Development Week 3: PHP Part 2

Advanced Arrays

  • Searching and Sorting Arrays
    • Sorting methods: sort(), rsort(), and usort() for indexed arrays.
    • Associative array sorting functions:
    • asort(), arsort(), uasort() (by value)
    • ksort(), krsort(), uksort() (by key)

PHP Superglobals

  • Definition: Predefined global arrays accessible from anywhere in your code.
  • Functions and Uses:
    • GET</code>,<code>_GET</code>, <code>_POST, etc. for handling form data and client information.

PHP Strings and Associated Functions

  • String Basics:

    • Strings can be made using either single or double quotation marks.
    • Variables can be embedded directly in strings.

  • String Manipulation:

    • Concatenation using . operator.
    • Various functions to manipulate strings:
    • strlen(), str_word_count(): counting characters and words.
    • strpos(), strrpos(): searching for the position of a character.
    • substr(): extracting substrings.

Functions for Array Manipulation

  • Common Array Functions:
    • array_shift(): Removes first element;
    • array_push(): Adds elements to the end;
    • array_merge(): Combines arrays, handling duplicates differently based on method used.
    • array_diff(), array_intersect(): Comparing arrays.

Binary Search

  • Description: Efficient way to find an element in a sorted array by repeated dividing the search interval in half.
  • Function:
    • Code implementation requires understanding of recursion:
  function binarySearch($arr, $start, $end, $x) {
      if($end < $start) return false;
      // (implementation continues)
  }

Quicksort Algorithm

  • Concept: Recursive sorting algorithm where you choose a pivot and sort lesser or greater values around it.
  • Complexity: Average time complexity is O(NextlogN)O(N ext{log} N).
  • Implementation:
  function quicksort(&$arr, $lo, $hi) {
      // (full implementation)
  }

Working with HTML Forms

  • Input Types:
    • Different basic and new HTML5 input types: text, password, file, etc.
  • Form Handling:
    • Understanding the difference between GET and POST methods (security, visibility in URL, etc.).

Form Data Validation

  • Functions:
    • empty(): Check if variables are undefined or empty.
    • isset(): Check if variable is declared.
    • Numeric Validation: Using is_numeric().

Further String Functions

  • Manipulating Strings:
    • str_replace(), str_ireplace(): For search and replace.
    • Tokenizing strings using strtok() and explode() to break strings into arrays.

Conclusion

  • OOP in PHP: Short overview on creating classes and objects in PHP.