student integral0
After following, you can keep track of his dynamic information in a timely manner
Courses in the relevant section：PHP data type NULL type
empty只要传回的值为null或者是false，则返回ture,反之为false。issue（可传多值，用逗号隔开）只要传回的值不是null，则返回false，反之返回ture
2018-06-090个赞
