php通过获取头信息判断图片类型

php通过获取头信息判断图片类型 无 $filename = '617.gif' ; function pictype ( $file ) { /*$png_header = "/x89/x50/x4e/x47/x0d/x0a/x1a/x0a"; $jpg_header = "/xff/xd8";*/ $header = file_get_contents ( $file , 0 , NULL , 0 , 5 ); //echo bin2hex($

php通过获取头信息判断图片类型

$filename = '617.gif' ; 

function pictype ( $file ) 
{ 
     /*$png_header = "/x89/x50/x4e/x47/x0d/x0a/x1a/x0a"; 
     $jpg_header = "/xff/xd8";*/ 

     $header = file_get_contents ( $file , 0 , NULL , 0 , 5 ); 

     //echo bin2hex($header); 
     if ( $header { 0 }. $header { 1 }== "/x89/x50" ) 
     { 
         return 'png' ; 
     } 
     else if( $header { 0 }. $header { 1 } == "/xff/xd8" ) 
     { 
         return 'jpeg' ; 
     } 
     else if( $header { 0 }. $header { 1 }. $header { 2 } == "/x47/x49/x46" ) 
     { 
         
         if( $header { 4 } == "/x37" ) 
             return 'gif87' ; 
         else if( $header { 4 } == "/x39" ) 
             return 'gif89' ; 
     } 
     
} 
echo pictype ( $filename );