DATATYPES IN PHP

Datatypes are used to specify type of variable data. In PHP, datatypes are mainly divided into 3 types –

1. Scalar Datatypes – Boolean, Integer, Float, String

2. Compound Datatypes – Array, Object

3. Special Datatypes – Resource, Null

SCALAR   DATATYPES

This datatype is further divided into 4 different types –

A. Boolean – This data-type can represent either true or false. In PHP value of true is 1 and value of false doesn’t contain any value

Example –

<?php

echo true;

echo false;

?>

Output –

1

is_bool – Using this function we can check input variable is Boolean or not.

Example –

<?php

$x=10;

echo is_bool($x);

$b="abc";

echo is_bool($b);

?>

(bool)var – Converts variable into boolean variable.

Example –

<?php

$b="abc";

$x=(bool)$b;

echo is_bool($x);

?>

Output –

1

B. Integer – This data-type can store numeric value.

is_int / is_integer – To check input variable is integer or not.

(int)var / (integer)var / intval(var) – To convert variable into integer variable.

Example –

<?php

$x="123";

$x=intval($x);

echo is_int($x);

echo "\n";

echo $x;

?>

Output –

1

123

Example –

<?php

$x="12Scott34";

$x=intval($x);

echo is_int($x);

echo "\n";

echo $x;

?>

Output –

1

12

Note – If $x=”Scott1234”, then value of $x=0

C. Float – This data-type can store decimal values.

is_float – This function checks input variable is float or not.

float(var) – Converts a variable into floating point number.

Example –

<?php

$x="12.34";

$x=(float)$x;

echo is_float($x);

?>

Output –

1

D. String – String is a collection of characters. In PHP, we can declare string in 3 ways – by using single quotations, by using double quotations, by using heredoc syntax.

Example –

<?php

echo 'Welcome';

echo "\n";

echo "Welcome";

echo "\n";

$x=100;

echo 'Value is $x';

echo "\n";

echo "Value is $x";

?>

Output –

Welcome

Welcome

Value is $x

Value is 100

Note – Variable in double quotation returns value of variables.

Heredoc – PHP supports heredoc syntax to avoid the conflicts what we are getting with single and double quotations.

Example –

<?php

$str = <<<DEMO

<input type='button' value="Click">

DEMO;

echo $str;

?>

COMPOUND   DATATYPES –

A. Array – Array is a collection of heterogeneous elements.

B. Object – Object is an instance of class.

SPECIAL    DATATYPES –

A. Resource – This data-type can refer external resources like database connections, file pointers etc

Example –

<?php

$x=mysql_connect("localhost","root","");

echo $x;

?>

Output –

Resource id #5

B. Null – In PHP, null is not a value. We can consider a variable as null variable based on 3 conditions

• ·        If variable is not set with any value

Example –

<?php

$x; // x is not set with any value

echo is_null($x);

?>

Output –

Notice: Undefined variable: x in C:\Users\om\workspace\PhpProjec\first.php on line 3

1

• ·        If variable is set with null

Example –

<?php

$x=null;

echo is_null($x);

?>

Output –

1

• ·        If variable’s value is unset

Example –

<?php

$x=100;

unset($x);

echo is_null($x);

?>

Output –

Notice: Undefined variable: x in C:\Users\om\workspace\PhpProjec\first.php on line 4

1

is_null – Using this function we can check input variable is null or not.