PHP determines whether the parameters after Url are legal

Question

For example, 1.php?123 correctly allows the output of 666

1. php?Does not output any characters except 123

What should I do with this? How to write please help me^_^^_^^_^^_^^_^^_^^_^^_^^_^^_^^_^^_^^_^^_^

Answer 1

explode('?',$url)

After splitting, take out the value after ? and then judge whether it is legal