isset(): Only when null and undefined, return true
empty(): "", 0, "0", NULL, FALSE, array(), undefined, all return true
is_null(): Only determine whether it is null, and a warning will be reported if it is not defined
').addClass('pre-numbering').hide(); $(this).addClass('has-numbering').parent().append($numbering); for (i = 1; i ').text(i)); }; $numbering.fadeIn(1700); }); });The above has introduced the differences between isset, empty and is_null, including the relevant aspects. I hope it will be helpful to friends who are interested in PHP tutorials.
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