w3resource

PHP: is_string() function

Description

The is_string () function is used to find whether a variable is a string or not.

Version:

(PHP 4 and above)

Syntax:

is_string (var_name)

Parameter:

Name Description Required /
Optional
Type
var_name The variable being checked Required Mixed*

*Mixed : Mixed indicates that a parameter may accept multiple (but not necessarily all) types.

Return value

TRUE if var_name is of type string is, FALSE otherwise.

Value Type: Boolean.

Example:

<?php
if (is_string("2663"))
echo "It is a string\n";
else
echo 'It is not a string';
var_dump(is_string('XYZ'));
var_dump(is_string("99"));
var_dump(is_string(123.05));
var_dump(is_string(false));
?>

Output:

It is a string  bool(true)  bool(true)  bool(false)  bool(false) 

View the example in the browser

Practice here online :

See also

PHP Function Reference

Previous: is_scalar
Next: isset



PHP: Tips of the Day

SQL injection that gets around mysql_real_escape_string()

Consider the following query:

$iId = mysql_real_escape_string("1 OR 1=1");    
$sSql = "SELECT * FROM table WHERE id = $iId";

mysql_real_escape_string() will not protect you against this. The fact that you use single quotes (' ') around your variables inside your query is what protects you against this. The following is also an option:

$iId = (int)"1 OR 1=1";
$sSql = "SELECT * FROM table WHERE id = $iId";

Ref : https://bit.ly/32q3bJ7