Example analysis PHP single file and multi-file upload

This article mainly gives you a detailed analysis of the PHP implementation of single file upload and multi-file upload code and problem-solving solutions, together with the study of reference, hope to help everyone.

$_files when is an empty array?

form submission Enctype not equal to Multipart/form-data when php.ini config file, file_uploads = Off uploaded file size > php.ini config file with maximum uploaded hours configured

As long as the occurrence of $_files is an empty array, the above problems may occur, must be fixed!

If you do not select any files, click the "Upload button" immediately, $_files will be an array with elements, each attribute in the element is an empty string, the error property is 4

Single File Upload

$_files Data structure

Array ('  filename ' = = Array (    ' name ' = ' = ' xxx.png ',    ' type ' = ' image/png ',    ' size ' = = 2548863,    ' tmp_name ' = '/img/sdsdsd.png ',    ' error ' = 0  )

Whether it is a single file or multiple file uploads, there are 5 fixed properties: Name/size/type/tmp_name/error

Multiple file uploads

Compared to single file upload, multi-file upload processing is more complicated than the front-end two kinds of multi-file upload form

Name same <form method= "post" enctype= "Multipart/form-data" >  <input type= "file" Name= "wt[]"/>  <input type= "File" Name= "wt[]"/>  <input type= "Submit" value= "Submit"/></form>//name different (simple point) < Form method= "POST" enctype= "Multipart/form-data" >  <input type= "file" name= "wt"/> <input  type= " File "name=" MMT "/>  <input type=" Submit "value="/></form> "

The back end of the $_files corresponds to a different data structure

Name of the same array (size=1) ' wt ' = = Array (size=5) ' name ' = = Array (size=2) 0 = + string ' New text document (2). txt ' ( length=26) 1 = string ' new text document. txt ' (length=22) ' type ' = = Array (size=2) 0 = String ' Text/plain ' ( length=10) 1 = String ' Text/plain ' (length=10) ' tmp_name ' = = Array (size=2) 0 = = String ' C:\Window     S\php1d64.tmp ' (length=22) 1 = String ' C:\Windows\php1D65.tmp ' (length=22) ' ERROR ' = = Array (size=2)  0 = int 0 1 = int 0 ' size ' = = Array (size=2) 0 = int 0 1 = int 1820//name different (simple point) array (size=2) ' wt ' = = Array (size=5) ' name ' = ' + string ' new text document (2). txt ' (length=26) ' type ' = = String ' Text/plain ' (length=   ' Tmp_name ' = = String ' C:\Windows\php39C7.tmp ' (length=22) ' ERROR ' = int 0 ' size ' + int 0 ' MMT ' = Array (size=5) ' name ' = + string ' new text document. txt ' (length=22) ' type ' = = String ' Text/plain ' (length=10) ' Tmp_name ' = = string ' C:\Windows\php39D8.tmp ' (length=22) ' ERROR ' = int 0 ' size ' + int 1820 

Field Error usage

Value: 1 The uploaded file exceeds the value of the Upload_max_filesize option limit in php.ini.

Value: 2 The size of the uploaded file exceeds the value specified by the Max_file_size option in the HTML form.

Value: 3 files are only partially uploaded.

Value: 4 No files were uploaded. Value: 5 The Upload file size is 0.