PHP file upload code usage example analysis

php file upload code writing process 1. First determine whether to upload the file 2. If there is any error, check again to see if there is an error in the upload. 3. If an error occurs, an error message will be displayed 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 Several things you must know when uploading files in php

 Upload:

Instructions: The action="upload.php" in the form tag means that when you click submit in this form, the upload command will be sent to the page called upload.php for processing. method="post" refers to sending in post mode. The enctype="multipart/form-data" attribute specifies which content type to use when submitting this form. When the form requires binary data, such as file content, please use "multipart/form-data", this attribute is necessary if you want to upload files. Type="file" in input specifies that the input should be processed as a file, and there will be a browse button behind the input.

A php processing page upload.php

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 the file ! );</script>";
}
?>

Upgrade the above php code. 1.upload.php

php file upload code_bbs .it-home.org





> ;


Please fill in the user name


Please briefly introduce the file



Please upload your file



< ;td>

2. uploadprocess.php

//Receive
$username=$_post['username'];
$fileintro=$_post['fileintro'];
< ;p>//echo $username.$fileintro;
//Get file information
/* echo "";
print_r($_files);
echo "";
*/
 //Get the size of the file
$file_size=$_files['myfile']['size'];
if($file_size>2*1024*1024){
echo "

Note: For example, if a picture file pic.jpg is processed with strrchr, strrchr(pic.jpg,'.'), it will return .jpg. Do you understand? This function returns the character after the last position of the specified character in the string. With substr(), we can get jpg, so 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.

Look at the random number file name section again and see the mt_srand() function. The manual calls it "sowing a better random number generator seed". It is actually 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 the needs. In this way, the random number will have a certain length, ensuring that the uploaded file does not have the same name.