How to upload files in php (process sharing)

With the rapid development of the Internet, uploading files has become an indispensable part of website development. As a commonly used scripting language, PHP also has many functions for file uploading. This article will introduce the process of uploading files in PHP.

1. Understand the basic knowledge of uploading files

Before uploading PHP files, we need to understand some basic knowledge. First of all, file upload needs to use the POST method in the HTTP protocol, because the POST method can transfer a large amount of data. Secondly, for security reasons, we need to set an upper limit on upload file size and upload file type restrictions.

2. Front-end page design

In the front-end page, we need a form to obtain the files uploaded by the user. The enctype attribute needs to be set to multipart/form-data in the form because ordinary forms do not support file upload by default. At the same time, we also need to add an input box of type file to select the uploaded file.

<input>
<input>

3. Back-end code implementation

In the php file for uploading files, we must first determine whether the file is uploaded successfully, then obtain relevant information about the file, and finally save the file to the server. Below is an example of a simple PHP file upload implementation.

//Determine whether the upload is successful
if ($_FILES"file" > 0) {

echo "上传失败";

} else {

//获取上传文件信息
$file_name = $_FILES["file"]["name"];
$file_size = $_FILES["file"]["size"];
$file_type = $_FILES["file"]["type"];
$file_temp = $_FILES["file"]["tmp_name"];
//限制文件类型和大小
$allowedExts = array("gif", "jpeg", "jpg", "png");
$extension = pathinfo($file_name, PATHINFO_EXTENSION);
if ((($file_type == "image/gif")
|| ($file_type == "image/jpeg")
|| ($file_type == "image/jpg")
|| ($file_type == "image/png"))
&& ($file_size <p>}</p><p>4. Summary</p><p>Through the above code implementation, we can see the process of file upload in PHP. During the front-end design process, pay attention to adding the multipart/form-data attribute to the form and the input box for selecting the file type. When implementing the back-end code, it is necessary to determine whether the file is uploaded successfully, obtain relevant information about the uploaded file, and limit the file type and size. All these details need to be handled consciously to ensure system reliability and security. </p>

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