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PHP gets the value of form form file field

伊谢尔伦

Apr 20, 2017 pm 01:34 PM

The function of the file field is to upload files or pictures. The file field has a unique attribute, which is used to specify the type of uploaded file. If you need to display the type of uploaded file, you can set this attribute.

In the development process, file or image uploading is an essential part of some website applications. For example, personal blogs upload personalized avatars, some forums share good learning materials, etc. This involves the knowledge of using forms to process file uploads. In PHP, we can use the $_FILES global array to handle it. Let’s take a look at the basic file upload processing part. First of all, it should be noted that being able to upload files must be a security risk, so when developing this part of the function, you must pay attention to the security of the website. What is discussed here is only the basic file upload part. It provides basic knowledge of PHP file upload so that friends can understand the simplest principles and code knowledge. There is less consideration in this aspect of security.

$_FILES: Variables submitted to the script via HTTP POST file upload. The contents of the

$_FILES array are as follows:

$_FILES['myFile']['name'] The original name of the client file.

$_FILES['myFile']['type'] The MIME type of the file, which requires the browser to provide support for this information, such as "image/gif".

$_FILES['myFile']['size'] The size of the uploaded file, in bytes.

$_FILES['myFile']['tmp_name'] The temporary file name stored on the server after the file is uploaded, usually the system default. It can be specified in upload_tmp_dir of php.ini, but setting it with the putenv() function will not work.

$_FILES['myFile']['error'] Error code related to the file upload. ['error'] was added in PHP 4.2.0. ["error"] value in

$_FILES["file"]["error"]:

UPLOAD_ERR_OK value: 0; No error occurs, file Upload successful

UPLOAD_ERR_INI_SIZE Value: 1; The uploaded file exceeds the value limited by the upload_max_filesize option in php.ini Value of

UPLOAD_ERR_PARTIAL Value: 3; Only part of the file is uploaded

UPLOAD_ERR_NO_FILE Value: 4; No file is uploaded, Value: 5; The uploaded file size is 0.

Here is a simple example. Select the file to be uploaded and click the "Upload" button. The absolute path of the file to be uploaded will be displayed above.

The specific development steps are as follows:

(1) Create a new index.php dynamic page, create a form form, add a file field and a submit button, the main The code is as follows:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>form</title>
</head>
<body>
<form action="index.php" method="post" name="form1">
  <input type="file" name="file" size="15">
  <input type="submit" name="upload" value="上传文件">
</form>
</body>
</html>

Description: This example implements getting the value of the file field, and does not implement the uploading of images, so there is no need to set the

form element

enctype="multipart/form-data"

Attribute. (2) Write a PHP statement, use the $_POST[] global variable to get the value of the menu list box, and use the

echo

statement to output. The PHP code is shown as follows:

<?php
echo $_POST["file"];     //输出要上传文件的绝对路径
?>

(3) Enter the running address in the browser and press the Enter key to get the running result as shown below:

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