FILTER_SANITIZE_NUMBER_INT

$str='41!5~6+7'; // Change this value to get different result
$str = filter_var($str,FILTER_SANITIZE_NUMBER_INT);
echo $str;

4156+7

 
filter_list:PHP list of filters available and how to display
filter_id:  ID Of filter used in PHP
filter_has_var:  checking the existance of variable in PHP
filter_var:  Validating variable using filter id
FILTER_VALIDATE_INT: Validating Integer with Maximum and Minimum range
FILTER_VALIDATE_EMAIL: Validating Email
FILTER_VALIDATE_URL: Validating URL with query string and path
FILTER_VALIDATE_IP: Validating IPV4 and IPV6 address
FILTER_VALIDATE_BOOLEAN: Validating boolean variable
FILTER_SANITIZE_STRING: Sanitize string
FILTER_SANITIZE_INT: Sanitize Integer, removes all except digits and plus minus sign
FILTER_SANITIZE_EMAIL: Sanitize email address