PHP image Upload implementation code with detailed notes

PHP image Upload implementation code with detailed notes, you can learn from your favorite friends. The code is as follows:
// Upload the image processing file
If ($ _ FILES ["file"] ["type"] = "image/gif ") | ($ _ FILES ["file"] ["type"] = "image/jpeg ") | ($ _ FILES ["file"] ["type"] = "image/pjpeg ")) & ($ _ FILES ["file"] ["size"] <100000) {// controls the types of images that can be uploaded. The last 100000 is the size of the images that can be uploaded.
If ($ _ FILES ["file"] ["error"]> 0 ){
Echo "Return Code:". $ _ FILES ["file"] ["error"]."
"; // Error returned
} Else {
/* // This is the information of the uploaded image. you can see the effect after removing the comments.
Echo "Upload:". $ _ FILES ["file"] ["name"]."
";
Echo "Type:". $ _ FILES ["file"] ["type"]."
";
Echo "Size:". ($ _ FILES ["file"] ["size"]/1024). "Kb
";
Echo "Temp file:". $ _ FILES ["file"] ["tmp_name"]."
";*/
If (file_exists ("userupload/". $ _ FILES ["file"] ["name"]) {
Echo $ _ FILES ["file"] ["name"]. "already exists .";
} Else {
Move_uploaded_file ($ _ FILES ["file"] ["tmp_name"], "userupload/". $ _ FILES ["file"] ["name"]);
}

$ Date = date ('ymdhis '); // Obtain the current time, for example, 20070705163148
$ FileName = $ _ FILES ['file'] ['name']; // Obtain the name of the uploaded file.
$ Name = explode ('.', $ fileName); // splits the file name by '.' to get the suffix and an array.
$ NewPath = $ date. '.'. $ name [1]; // you can find a new file named '20070705163148.jpg ', which is the new path.
$ OldPath = $ _ FILES ['file'] ['tmp _ name']; // temporary folder, that is, the previous path
Rename ("userupload/". $ fileName, "userupload/". $ newPath );

// Here, you can write your SQL statement. The image address is "userupload/". $ newPath

?>