Zend_Validate_Digit validates if a given value contains only digits.
There are no additional options for Zend_Validate_Digits:
To validate if a given value contains only digits and no other characters, simply call the validator like shown in this example:
<?php
$validator = new Zend_Validate_Digits();
$validator->isValid("1234567890"); // returns true
$validator->isValid(1234); // returns true
$validator->isValid('1a234'); // returns false
Validating numbers
When you want to validate numbers or numeric values, be aware that this validator
only validates digits. This means that any other sign like a thousand separator or
a comma will not pass this validator. In this case you should use
Zend_Validate_Int or
Zend_Validate_Float.