When working with variables in PHP, it’s important to know the difference between the isset(), empty(), and is_null() functions. These functions are commonly used to determine whether a variable has a value or not. In this tutorial, you will learn difference between PHP empty() vs isset() vs is_null() function with its definition, syntax, require parameters and with examples.
isset vs empty vs is_null in PHP
Let’s see the isset(), empty(), and is_null() along with their definition, syntax, usage, and difference:
- isset() function
- empty() function
- is_null() function
isset() function
isset() is a inbuilt function of PHP. which is used to test/check if a variable value is set or not. This function returns the result as a boolean form (TRUE / FALSE).
Note:- If the variable value is set, this function will return the boolean value true. Otherwise, this function will return the boolean value false.
Syntax:
isset(variable, ….);
Parameters | isset() function
The PHP isset() function will accept multiple variables as shown in the above-given syntax of isset() function.
Note: You can pass more than one variable in this function, but this function will return true only if all of the variables are set.
Example PHP isset() function
Let’s take an example of a function isset(). Here, we have two variables. The first name is variable and the second is one name is variable1. We will first check and test it with isset() set the value in the variable. And also we will not set value of the second variable, we will check with an isset() function.
You can see the example below: “
<?php
// PHP code to check without set variable value
$variable;
if( isset( $variable ) ) {
print_r(" The variable value is set, checked by isset() ");
}else{
print_r(" The variable value is not set, checked by isset() ");
}
echo "<br>";
// PHP code to check with set variable value
$variable2 = 'hello world';
if( isset( $variable1 ) ) {
print_r(" The variable value is set, checked by isset() ");
}else{
print_r(" The variable value is not set, checked by isset() ");
}
?>
empty() function
empty() is a inbuilt function of PHP. and commonly is to test/check if a given variable value is empty or not. This function returns the result as a boolean form (TRUE / FALSE).
Note:- If the variable value is not empty, this function will return the boolean value false. Otherwise, return the boolean value true.
Syntax:
empty( $variable )
Parameters | empty() function
The empty() PHP function accepts one parameter only. You can see the syntax of this variable above.
Example of empty() function
In the example below, we have two variables, the first is num1 and the second is num2. We will first check and test it with empty() giving the value in the variable. And also we will set the null value of the second variable, we will check with an empty function.
You can see the example below:
<?php
// PHP Code to check first variable
$variable;
if( empty( $variable ) ) {
print_r(" The variable value is empty, checked by empty() ");
}else{
print_r(" The variable value is not empty, checked by empty() ");
}
echo "<br>";
// PHP Code to test variable with empty()
$variable2 = 'PHP world!';
if( empty( $variable2 ) ) {
print_r(" The variable value is empty");
}else{
print_r(" The variable value is not empty");
}
?>
is_null() function
is_null() function is an inbuilt PHP function. Which is used to find / test whether a variable value is NULL or NOT. This function returns the result as a boolean form (TRUE / FALSE).
Note:- If the variable value is null, this function will return the boolean value true. Otherwise, this function returns the boolean value false.
Syntax:
is_null( $variable )
Parameters | is_null() function
The is_null() PHP function accepts one parameter only. You can see the syntax of this variable above.
Example of is_null() function
In the example below, we have two variables, the first is variable and the second is variable1. We will set the null value of the variable, we will check with an is_null() function. Also, We will first check or test it with is_null() giving the value in the variable2.
You can see the example below:
<?php
// PHP Code or scritp to explain php is_null() function
$variable = null;
if( is_null( $variable ) ) {
print_r(" The variable value is null ");
}else{
print_r(" The variable value is not null");
}
echo "<br>";
// PHP Code to test variable with is_null()
$variable2 = '10';
if( is_null( $variable2 ) ) {
print_r(" The variable value is null ");
}else{
print_r(" The variable value is not null");
}
?>
Uses of these functions:
| Functions | “” | “apple” | NULL | FALSE | 0 | undefined |
| empty() | TRUE | FALSE | TRUE | TRUE | TRUE | TRUE |
| is_null() | FALSE | FALSE | TRUE | FALSE | FALSE | ERROR |
| isset() | TRUE | TRUE | FALSE | TRUE | TRUE | FALSE |
Question 1 :- what is the difference between is_null() and isset()?
Answer:-
You can see the difference between empty() and is_null() function:
| isset() function | is_null() function |
| it returns true only when the variable is not null. | it returns true only when the variable is null. |
Question 2:- What is the difference between is_null() and isset()?
Answer:-
The main difference between isset and empty in php is that, You can see below
| isset() function | empty() function |
| it returns true only when the variable is not null. | it will return true if the variable is an empty string,0, NULL ,or False value. |
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