You can check the length of a string by using the strlen() function. If you pass it a string, this function will return its length. For example, the result of this code is 5:
echo strlen(“hello”);
You can use the strlen() function for validating input data. Consider the email address on the sample form, stored in $email. One basic way of validating an email address stored in $email is to check its length. By our reasoning, the minimum length of an email address is six characters—for example, a@a.to if you have a country code with no second-level domains, a one-letter server name, and a one-letter email address. Therefore, an error could be produced if the address is not at least this length
if (strlen($email) < 6){
echo 'That email address is not valid';
exit; // force termination of execution
}
Other example of strlen in php
<?php
$str = 'abcdef';
echo strlen($str); // 6
$str = ' ab cd ';
echo strlen($str); // 7
?>
<?php
$attributes = array('one', 'two', 'three');
if (strlen($attributes) == 0 && !is_bool($attributes)) {
echo "We are in the 'if'\n"; // PHP 5.3
} else {
echo "We are in the 'else'\n"; // PHP 5.2
}
?>
<?php
echo strlen("Hello");
?>
Output
5