Php file Upload judgment file type solution

Php uploads a file to determine the file type. I want to upload a csv file now. how can I determine in php that the file type is csv? Note: in addition to determining the extension, how can we determine the extension ?? ------ Solution ------------------ $ _ FILES [& quot; file & quot;] [& quot; type & quot;] ------ php uploads a file to determine the file type
I want to upload a csv file now,
In php, how does one determine that the file type is csv?

Note:
In addition to determining the extension, what else can be used to determine the segment ??

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$ _ FILES ["file"] ["type"]
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Discussion

$ _ FILES ["file"] ["type"]

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Learning !!!!!!!!!!!!!!!
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The landlord has to complicate simple things. No way!
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A good way to spread it online

PHP code

Function ftype ($ filename) {$ file = fopen ($ filename, "rb"); $ bin = fread ($ file, 2 ); // read-only 2-byte fclose ($ file); $ strInfo = @ unpack ("C2chars", $ bin); $ typeCode = intval ($ strInfo ['chars1']. $ strInfo ['chars2 ']); $ fileType = ''; switch ($ typeCode) {case 7790: $ fileType = 'exe'; break; case 7784: $ fileType = 'midi '; break; case 8297: $ fileType = 'rar'; break; case 255216: $ fileType = 'jpg '; break; case 7173: $ fileType = 'GIF'; break; case 6677: $ fileType = 'bmp '; break; case 13780: $ fileType = 'PNG'; break; default: $ fileType = 'unknown ';} return $ fileType ;}
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I think the method on the eighth floor has been used to determine to the greatest extent possible. according to the landlord's meaning, how does the uploaded file determine whether the content is in csv format (do not trust the extension ), you can only obtain the content in the file and determine whether it is a csv file based on the content in the file. However, this method must be implemented in the background, that is, the file has already been uploaded, it is useless to determine after uploading. Therefore, I personally think that there is no good solution to determine the content format without uploading.
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   Discussion
   

   
I mean, the csv file is not used. are the files separated?
   

   
Aa, bb, cc, dd
   
Ee, ff, gg, hh
   

   
Files like this
   
According to the statement on the eighth floor, the typeCode of this file is 131112
   
However
   

   
Aa, "B
   
B ", cc, dd
   
Ee, ff, gg, hh
   

   
This is also the correct csv format, but the typeCode of this file is 105105
   
......