In an echo statement, the comma, and dot operator are used to join the strings.

Elements in an array have same type are called vector array.

Hashes are also called PHP arrays.

count() function is used to count the number of elements in an array.

1. Using sizeof() function we can check.
2. If the size of array is zero then array is empty.

PHP functions that start with a double underscore "_ _" are called magic functions in PHP.

For a function to return a value, use the return statement
function sum($x, $y)
<?php
{\(\$\)z = \(\$\)x + \(\$\)Y; return \(\$\)z;
}echo "5+10=". sum(5, 10). "<br>";
echo "7+13= ". sum(7, 13). "<br>";
echo "2+4= ". sum(2, 4);
?>

A function is a type of sub routine or procedure in a program.

A function declaration part will be executed by a call to the function. Programmer has to create Function Calling part inside the respective program.
SYNTAX:
function Name ( );

The index can be assigned automatically in a collection of data set

A multidimensional array is an array containing one or more arrays.

The index can be assigned automatically in a collection of data set.

Associative arrays are arrays that use named keys that you assign to them.

array(key= >value,key= >value,key= >value,etc.);
key = Specifies the key (numeric or string value = Specifies the value

1. The array() function is used to create an array.
2. In PHP,there are three types of arrays:
i). Indexed arrays - Arrays with numeric index
ii). Associative arrays - Arrays with named keys
iii). Multidimensional arrays - Arrays containing one or more arrays