php Tutorial File Upload
Before you can use PHP to manage your uploads, you first need to build an HTML form that serves as the user interface for uploading files
. Have an example look below and save an editable HTML code.
When there are some rules that need to be constructed Follow the HTML form. First, make sure the form uses the POST method. Second, the form
requires the following attributes: character encoding = "multiple/form-data". It specifies the content type used when submitting
information to the server. Without these requirements, your file cannot be uploaded.
Another thing to note is that the hidden form field named MAX_FILE_SIZE sets the value. Some web browsers
actually reflect this field and will not allow users to upload files larger than this number (in bytes). You should
set this value to match the maximum upload size, set in the php.ini file. This is a set with
upload_max_filesize, the default value is 2MB. But it still doesn't guarantee that your script won't deliver files that are
inches larger. The danger is that an attacker will try to send you a request for several large files and fill out the file system, which is where PHP stores the decoded files. Set the post_max_size directive in php.ini to the maximum
file size you want (must be greater than upload_max_filesize). The default value is 10MB. This directive controls the maximum size of POST data allowed within a
request. Also, make sure that file_uploads is set to On in your php.ini file
.
At least, there is a look at the input tag attribute: type="file". It is used to specify the input
element for file selection control. This provides a file URI in place that you need to type into a "Browse" button and can be used as an alternative to the
URI input.
After the user enters a file URI and clicks the submit button a copy of the file will be sent to the server and the user will
be redirected to upload.php. This PHP file will handle form data.
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Handling form data (PHP code)
When the file is uploaded and PHP creates a temporary copy of the file and sets up the superglobal variable $_FILES Array,
contains information about the file. For each file, there are 5 data. We have uploaded the field named
as 'uploaded_file', so the following data will be present:
Variable $_FILES ["uploaded_file"] ["name"] The original of the file uploaded from the user's machine Name
Variable $_FILES["uploaded_file"]["type"] The MIME type of the uploaded file (if the browser
provides the type)
variable $_FILES["uploaded_file"] ["tmp_name"], where the file is temporarily stored on the server
The following example accepts an uploaded file and saves it in the upload directory. It allows uploading only JPEG
images under 350Kb. The code itself is fairly self-explanatory, but we'll give it some explanation. There is an example in the look and save
save this PHP code as upload.php.
//Сheck that we have a fileif((!empty($_FILES["uploaded_file"])) && ($_FILES['uploaded_file']['error']
== 0)) { //Check if the file is JPEG image and it's size is less than 350Kb
$filename = basename($_FILES['uploaded_file']['name' ]);
$ext = substr($filename, strrpos($filename, '.') + 1);
if (($ext == "jpg") && ($_FILES["uploaded_file"] ["type"] == "image/jpeg")
&&
$newname = dirname(__FILE__).'/upload/'.$filename;
//Check if the file with the same name is already exists on the
server if (!file_exists($newname)) {
//Attempt to move the uploaded file to it's new place
if ((move_uploaded_file($_FILES['uploaded_file']
['tmp_name'],$newname))) {
echo "It's done! The file has been saved as: ".$newname; occurred during file upload!";
}
} else {
echo "Error: File ".$_FILES["uploaded_file"]["name"]." already
exists" ;
} else {
echo "Error: Only .jpg images under 350Kb are accepted for upload";
}
} else {
echo "Error: No file uploaded ";
}
?>
Before uploading the file you need to determine if the file is actually uploading anything. After that, we check the files uploaded on
, JPEG images, and their sizes are less than 350Kb. Next, we determine the path, which is the name of these files where we want to save this file and check if there is already a server. When all checks pass,
we copy the file to a permanent location using the move_upload_file() function. This feature also confirms that the
file you want to process is a legitimate file as a result of the user upload. If the file is uploaded successfully, the corresponding
message will appear.
Note: Make sure PHP has allowed reading and writing of temporary files in the directory where you want to copy the files.
This example is actually very simple. It is proposed to demonstrate how to use PHP to upload files. For example, you can add
new conditions and allow uploading of GIF and PNG images, or any other kind of files you need. If you are new to this tutorial
using PHP might be a good place to start.
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php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

在PHP中,可以利用implode()函数的第一个参数来设置没有分隔符,该函数的第一个参数用于规定数组元素之间放置的内容,默认是空字符串,也可将第一个参数设置为空,语法为“implode(数组)”或者“implode("",数组)”。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。


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