Why cannot the file domain content be displayed?

Why cannot the file domain content be displayed? & Lt ;! DOCTYPEhtmlPUBLIC & quot;-// W3C // DTDXHTML1.0Transitional // EN & quot; why is the http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd&q unable to display file domain content?





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Echo $ _ POST [a];
?>



Why is the echo $ _ POST [?
Change to echo $ _ POST [sub]; but you can output it!

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Echo $ _ FILES ["a"] ["name"];
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Because Yes
Php does some special processing, so a is not in $ _ POST, but in $ _ FILES

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$ _ FILES ["a"] ["name "];
The $ _ POST in the book you mentioned does not include the upload control.