PHP is a widely-used, open source general-purpose scripting language embedded within HTML that has become particularly popular for web development projects and can handle various file types.
This tutorial introduces PHP’s fundamentals, such as control statements, functions, arrays and strings. Additionally, it covers how to effectively use logic operators such as comparison operators.
Table of Contents
PHP functions are reusable blocks of code that perform specific actions, taking user input, processing it and returning an output. There are over 700 built in functions available that do specific tasks – and custom functions allow you to further organize and simplify your codebase.
PHP functions can be identified using the keyword function and enclosed within curly brackets (). Their names must begin with “function”, then be followed by any number of parameters separated by commas – these variables must first be declared before calling a function.
Variables can be passed to functions either by value or reference. Passing by value ensures that no changes will take place outside the function, but if you want to use an object twice then pass by reference would be best.
When passing variables to functions, those functions will assign each variable its own data type; this process is known as variable scoping. If global flag is enabled on an assigned variable then that variable can also be accessible outside the function as well.
PHP contains various special functions that can be used to perform routine tasks such as finding the location of substrings in strings. One such function, strpos(), returns an index that specifies where in a string the beginning of any given substring begins in a string; str_replace() replaces patterns with another string pattern.
PHP variables are used to store values in scripts. Their names start with a dollar sign ($) and can contain letters, numbers or underscore characters – the latter of which may also contain special symbols – just as in other programming languages – though unlike some there is no limit on character count for variable names in PHP; they must always begin with either letters or underscore characters (never numbers!). However, PHP variables must always begin with either letters or underscore characters rather than starting out as numbers!
Variables in PHP can be stored as strings, integers, floats or Booleans depending on their value; string variables may store either true or false data while double precision decimal numbers (floats) only store either true or false values. Converting between types is known as type juggling in PHP and allows the same variable to hold various forms of information at once.
When creating variables, it’s essential that a consistent naming convention be implemented throughout your code and easily understandable by other developers. You might decide to use underscores between words for separation or use upper and lower case letters in an identical fashion (known as Camel Case). You should adhere to the convention when assigning variable names within code or else your program could generate errors when trying to access variables.
PHP offers global and superglobal variables in addition to local ones. Global variables are stored within $_SERVER, $_POST and $_GET global scopes for easy access throughout scripts; typically used as parameters when calling functions. Superglobal variables exist as globals as well, typically stored under $_POST global scope and used similarly.
Arrays are special variable types that store many values at once, making it easier to manage large volumes of information. PHP offers three different kinds of arrays – indexed, associative and multidimensional. An indexed array uses numeric indexes to access its values in linear order – perfect for retrieving values from databases tables.
Associative arrays are similar to indexed arrays, except they use strings instead of numbers as index keys and the short array syntax. Associative arrays are useful for storing sets of values – like names – that do not fit in one variable variable variable; you can use foreach( ) loop to print each item in an associative array.
Multidimensional arrays can be accessed using more than one set of square brackets to navigate deeper into them, where each set represents a new key level. This method is useful for sorting arrays with many elements and creating them as arrays first is essential to this process.
Arrays are an integral component of PHP programming, making your code easier to read and maintain. Utilizing next, prev, reset and end functions to manipulate arrays will make your code more readable and maintainable. When manipulating them you can use functions such as next, prev, reset and end to manipulate internal pointers within an array. You may also need to loop through an array’s values reading or changing them which can be accomplished using foreach( ) or for( ) loops – the latter pair allows this. To create arrays from existing variables use array( ) language construct.
Strings are simple data types in PHP that contain alphabetic characters arranged in sequence; these strings may include letters, numbers, symbols or spaces. As the most fundamental data type available to PHP programmers, strings can be used for various applications and purposes. PHP offers multiple functions dedicated to working with strings for manipulation or querying of its value.
PHP offers multiple ways of declaring strings, each with their own use. One simple solution is using single quotes around the string – this syntax works similarly to Heredoc or Nowdoc methods but without expanding variables and escape sequences when declaring single quote strings; therefore this approach works best when string values don’t require parsing.
Another method for creating strings in PHP is using double quotes around each string. This syntax is more readable, suitable for any string, and works particularly well when variables need to be escaped from their scopes. Furthermore, unlike Heredoc or Nowdoc syntaxes which expand variable names as they parse along, double quote strings expand variables when parsed as well.
PHP data types are mostly strings. While certain functions return directly-stretched strings for storage purposes – known as serialization – others convert these values to strings as needed and store them instead – providing more convenient storage solutions. To inspect these data types more closely use var_dump() and print_r() functions.
PHP string functions include strlen() and strrv(), which return the length and reverse respectively of strings, and can significantly reduce the amount of code necessary when working with them. While there are other string functions available in PHP that might seem confusing at first glance, familiarizing yourself with them first before diving deeper is wise.
File management in PHP is an integral aspect of web application creation. It involves reading, writing and appending to files as part of web applications, with various functions like fopen(), fclose() and readfile() available to manage them safely. When working with files it is imperative that all actions taken be executed carefully as errors when manipulating them could cause serious systemic harm, including deletion or corruption of its contents.
PHP files are text files containing PHP script source code that when executed by a web server using its PHP engine, generate an HTML web page that is then sent directly to users’ browsers. They’re often used by website developers for adding extra features to websites such as video embeds or contact forms.
PHP is a fantastic server-side programming language, but not suitable for desktop development due to its lack of graphical user interface and required separate environment for running. As such, most developers utilize one of two tools like WAMPServer or XAMPP (available for Windows, macOS or Linux), to compile code before testing on web servers before testing the result in browsers such as Firefox or Internet Explorer. Users who only wish to view code in text editor windows such as Visual Studio Code or Notepad++ as opposed to compiling can install one such as Visual Studio Code or Notepad++ that support PHP that provides them with an environment in addition to seeing PHP code within text editor windows for viewing its source code!