


Detailed explanation of the usage of PHP file upload code_PHP tutorial
This article is an article suitable for PHP beginners to tell you how to edit the PHP file upload code. Before editing, we need to understand a few points and understand the FILES global variable. There are friends who need to learn PHP file upload. You can refer to this article.
php file upload code writing process
1. First determine whether to upload the file
2. If there is any error, please check again to see if there is an error in the upload
3. If an error occurs, an error message will be prompted
4. If there are no errors, then determine the file type
5. If the type meets the conditions, then determine whether the file exists in the specified directory
6. If not, move the file to the specified directory
Some things you must know when uploading files in php
$_FILES['myfile']['name'] refers to the name of the uploaded file
$_FILES['myfile']['type'] refers to the type of file being uploaded
$_FILES['myfile']['size'] refers to the size of the uploaded file, in bytes (B)
$_FILES['myfile']['tmp_name'] refers to the name of the temporary copy file of the uploaded file stored in the server. After the file is moved to the specified directory, the temporary file will be automatically destroyed.
$_FILES['myfile']["error"] refers to the status code of errors that may occur during file upload. The meaning of each status will be explained later.
Let’s take a look at the HTML part first.
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Description:
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if($_FILES['myfile']['name'] != '') { <🎜> if($_FILES['myfile']['error'] > 0) { echo "Error status:" . $_FILES['myfile']['error']; } else { move_uploaded_file($_FILES['myfile']['tmp_name'] , "uploads/" . $FILES['myfile']['name']); echo "<script>alert(Upload successful!);</script>"; } } else{ echo "<script>alert(Please upload files!);</script>"; } ?> |
The above is super simple, let’s upgrade it now
1. upload.php
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2. uploadProcess.php
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"; Print_r($_FILES); echo ""; */ //Get the file size $file_size=$_FILES['myfile']['size']; If($file_size>2*1024*1024){ echo ""; exit(); } //Get file type $file_type=$_FILES['myfile']['type']; If($file_type!="image/jpeg" && $file_type!="image/pjpeg"){ echo "The file type can only be jpg format"; exit(); } //Determine whether the upload is OK If(is_uploaded_file($_FILES['myfile']['tmp_name'])){ //Get the uploaded file and transfer it to the directory you want $upload_file=$_FILES['myfile']['tmp_name']; //To prevent image overwriting problems, create a folder for each user $user_path=$_SERVER['DOCUMENT_ROOT']."/file/up/".$username; If(!file_exists($user_path)){ mkdir ($user_path); } //$move_to_file=$user_path."/".$_FILES['myfile']['name']; //Prevent users from uploading the same username $file_true_name=$_FILES['myfile']['name']; $move_to_file=$user_path."/".time().rand(1,1000).substr($file_true_name,strripos($file_true_name,".")); //echo $upload_file.$move_to_file; //Chinese needs to be transcoded If(move_uploaded_file($upload_file,iconv("utf-8","gb2312","$move_to_file"))){ echo $_FILES['myfile']['name']."Upload successful"; }else{ echo "Upload failed"; } }else{ echo "Upload failed"; } ?> Note: Let me give you an example, and everyone knows, for example, a picture file pic.jpg, we use strrchr to process it, strrchr(pic.jpg,'.'), it will return .jpg, do you understand? This function returns the character following the last occurrence of the specified character in the string. With substr(), we can get jpg, so that we can get the file extension to determine whether the uploaded file conforms to the specified format. This program puts the specified format in an array, which can be added as needed during actual use. Next, look at the file name that generates random numbers. We see the mt_srand() function. The manual calls it "sowing a better random number generator seed". In fact, it is a function that initializes a random number. The parameter is (double )microtime() * 1000000, if this is not a parameter here, a random number will be automatically set. Of course, this does not meet our needs. In this way, the random number will have a certain length, ensuring that the uploaded file does not have the same name

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