Basics
Sample Program
<?php
echo "Hello, world!!!!"
?>
- echo : echo is used to output data to the console/screen.
- print : print is also used to output data to the screen. Both
echo and print are more or less same with small differences, echo doesn't have a return value but print has a return value. echo can have multiple arguments but print takes only one argument. Echo is faster than print comparatively.
- fscanf : fscanf is used to read input from console
- // : single line comment
- # : Single line comment
- /* */ : Multi line comment
Data Types
PHP is a loosely typed language and hence you no need to declare variables with data types.
However, below are the different datatypes in PHP.
| Data type | Usage |
|---|
| Integer | $x = 999999; |
| String | $str = "Hello World" |
| Float | $x = 79.53 |
| Boolean | $isAvailable = TRUE; |
| Array | $arr = array("iPhone", 1000, TRUE); |
| Object | $obj = new className(); |
| Null | $str = null; |
| Resource | $conn = mysqli_connect(localhost,"root","userName","password"); |
Variables
$variable_name = value;
Constants
Using define()
define(name, value, case_insensitive)
- name: name of the constant
- value: value of the constant
- case_insensitive: Specifies whether the constant name should be case-insensitive or not. By default it is set to false.
define("GREETING","Hello you! How are you today?");
echo constant("GREETING");
Using const keyword
const MESSAGE = "Happy learning!";
String Functions
| String Function | Usage |
|---|
| strlen() | echo strlen("One Compiler"); |
| str_word_count() | echo str_word_count("Hello world! Happy Learning!!"); |
| strrev() | echo strrev("One Compiler"); |
| str_replace() | echo str_replace("bar", "Foo", "Good morning bar!"); |
| strpos() | echo strpos("Hello world! Happy Learning!!", "appy"); |
| str_repeat() | echo str_repeat("Hello! Happy Learning!!", 4); |
| rtrim() | echo rtrim(" Right space will be trimmed "); |
| ltrim() | echo rtrim(" left space will be trimmed "); |
| strcmp() | echo strcmp(string1,string2); |
Operators
| Operator type | Description |
|---|
| Arithmetic Operator | + , - , * , / , %, ++, -- |
| comparision Operator | < , > , <= , >=, != , == |
| Logical Operator | && , ||, ! |
| Assignment Operator | = , += , -= , *= , /= , %= |
| Conditional Operator | ? : |
Arrays
$arrName = array(values..);
1. Indexed arrays
$directions = array("East", "West", "North", "South");
2. Associative arrays
$capitals = array("Japan" => "Tokyo", "India" => "New Delhi","United Kingdom" => "London","United States" => "Washington, D.C.","China" => "Beijing");
3. Multi dimensional arrays
// two-dimensional array
$num = array(
array(1,2,3),
array(4,5,6),
array(7,8,9)
);
Conditional Statements
1. If
if(conditional-expression)
{
//code
}
2. If-else
if(conditional-expression)
{
//code
} else {
//code
}
3. If-else-if
if(conditional-expression-1)
{
//code
} else if(conditional-expression-2) {
//code
} else if(conditional-expression-3) {
//code
}
....
else {
//code
}
4. Nested-If
if(conditional-expression-1) {
//code
if(conditional-expression-2) {
//code
if(conditional-expression-3) {
//code
}
}
}
5. Switch
switch(conditional-expression){
case value1:
//code
break; //optional
case value2:
//code
break; //optional
...
default:
//code to be executed when all the above cases are not matched;
}
Loops
1. For
for(Initialization; Condition; Increment/decrement){
//code
}
2. Foreach
foreach ($array as $value) {
//code
}
3. While
while(condition){
//code
}
4. Do-while
do{
//code
}while(condition);
Functions
function functionName() { // defining a function
//code
}
functionName (parameters); //calling a function
Date
(PHP 4, PHP 5, PHP 7, PHP 8)
date_default_timezone_set('America/Los_Angeles');// set default time zone( Useful while deploying to server)
$dateVal=date("F j, Y, g:i a"); // March 10, 2001, 5:16 pm
File
| Function | Syntax | Description |
|---|
| readfile() | readfile(myfile.txt) | prints the contents of myfile.txt in browser |
| fopen(filename, mode) | fopen("myfile.txt", "r") | opens myfile.txt in read mode |
| fread(file, length) | fread($fptr, filesize("myfile.txt")) | read file upto length and stores in file pointer |
| fclose() | fclose($fptr) | The fclose() function closes an open file pointer |
MySQLi Functions
These functions allow you to access MySQL database server.
| Function | Description |
|---|
| mysqli_connect() | It opens a non-persistent MySQL connection |
| mysqli_affected_rows() | It returns the number of affected rows |
| mysqli_connect_error() | It shows the Error description for the connection error |
| mysqli_fetch_all() | It fetches all result rows as an array |
| mysqli_fetch_array() | It fetches a result row as an associative, a numeric array, or both |
| mysqli_fetch_assoc() | It fetches a result row as an associative array |
| mysqli_fetch_row() | It fetches one row from a result set and returns it as an enumerated array |
| mysqli_kill() | It kills a MySQL thread |
| mysqli_close() | It closes a database connection |
| mysqli_query() | It runs any sql query from database in php |
| mysqli_num_rows() | It counts number of rows affected after running any sql query |
Global Variables - Superglobals
| Variables | Usage |
|---|
| $_SERVER | $_SERVER['REQUEST_METHOD'] Returns the request method used to access the page (such as POST) |
| $_POST | name=_POST['fname'] collects value from a form(name='fname') and stores to $name after submitting an HTML form with method="post" |
| $_GET | $_GET can also collect data sent in the URL |