Introduction to commonly used file operation reading and writing functions in PHP_PHP Tutorial

This article introduces the following commonly used file operation functions file_get_contents reads the entire file content fopen creates and opens files fclose closes the file fgets reads a line of file content file_exists checks whether a file or directory exists file_put_contents writes to file fwrite writes files

Use PHP built-in function file_exists to check whether a file or directory exists. The file_exists function returns TRUE if the file or directory exists, or FALSE if it does not exist.

The following is a simple example code to check whether the file exists:

代码如下	复制代码
$filename = "C:blablaphphello.txt"; if (file_exists($filename))  {echo "The file $filename exists."; }else  { echo "The file $filename does not exist." ;}?>

If the file exists, the displayed result of executing the PHP file is:

The file C:blablaphphello.txt exists.
If the file does not exist, the displayed result of executing the PHP file is:

The file C:blablaphphello.txt does not exist.
You can also use the file_exists function to test whether a directory exists. The sample code is as follows:

The code is as follows

Copy code

代码如下	复制代码
if (file_exists("C:blablaphp"))   {echo "yes";} else   {echo "no";}

if (file_exists("C:blablaphp"))

{echo "yes";}
else

{echo "no";}

The entire file content can be read using the PHP built-in function file_get_contents.

The file_get_contents function reads the entire file and returns a string. The simplest way to write file_get_contents is as follows:

file_get_contents(filepath)

For example, you have a .txt file with the path:

代码如下	复制代码
$f = file_get_contents("C:blablaphphello.txt"); echo $f;?>

C:blablaphphello.txt

The following php code uses the file_get_contents function to read the file and output the file contents:

The code is as follows	Copy code
$f = file_get_contents("C:blablaphphello.txt"); echo $f;?>

Note: Since the file path contains backslashes, and in PHP strings, the backslashes need to be escaped and represented by two backslashes. (If you forget the escape of some special characters in PHP, please read the PHP string mentioned above.)

The return value of the file_get_contents function is the read file content string. If an error occurs, FALSE is returned.

代码如下	复制代码
$f = fopen("c:datainfo.txt", "r"); ?>

A file can be opened using the PHP built-in function fopen. Open file The simplest syntax of fopen is as follows: fopen(filepath,mode) Here is an example of PHP code to open a file:

The code is as follows	Copy code
$f = fopen("c:datainfo.txt", "r"); ?>

Among them, c:datainfo.txt is the file path, and r indicates that the mode of opening the file is read only mode.

The fopen function has the following modes for opening files:

Mode Description
r Read only, the file pointer is at the beginning of the file.
r+ for reading and writing, the file pointer is at the beginning of the file.
w is write only, the file pointer is at the beginning of the file, and the file length is truncated to 0.

Create the file if it does not exist.

w+ reads and writes, the file pointer is at the beginning of the file, and the file length is truncated to 0.

Create the file if it does not exist.

a is write only, the file pointer is at the end of the file.

Create the file if it does not exist.

a+ for reading and writing, the file pointer is at the end of the file.

Create the file if it does not exist.

x is write only, the file pointer is at the beginning of the file.

If the file already exists, the fopen () function returns FALSE and generates an E_WARNING level error.

Create the file if it does not exist.

x+ for reading and writing, the file pointer is at the beginning of the file.

If the file already exists, the fopen () function returns FALSE and generates an E_WARNING level error.

Create the file if it does not exist.

If the file is successfully opened, the return value of the fopen function is a file pointer resource. If an error occurs, FALSE is returned.

Create file
Selecting an appropriate value for the fopen function parameter mode, you can create a file with fopen, for example:

The code is as follows

Copy code

代码如下	复制代码
$f = fopen("c:data101.txt", "w"); $f = fopen("c:data102.txt", "w+"); $f = fopen("c:data103.txt", "a"); $f = fopen("c:data104.txt", "a+"); $f = fopen("c:data105.txt", "x"); $f = fopen("c:data106.txt", "x+"); ?>

$f = fopen("c:data101.txt", "w"); $f = fopen("c:data102.txt", "w+");

$f = fopen("c:data103.txt", "a");

$f = fopen("c:data104.txt", "a+");

$f = fopen("c:data105.txt", "x");
$f = fopen("c:data106.txt", "x+");

?>

Use the PHP built-in function fgets to read a line of the file.

The syntax for fgets to read a line of file content is:

fgets(filepointer)
Below we give an example of how to read a file line by line.

代码如下	复制代码
$f= fopen("C:blablaphpsites.txt","r"); while (!feof($f)){  $line = fgets($f);  echo "site: ",$line," "; } fclose($f);?>

Suppose we have a sites.txt file with three lines and the following content: woyouxian.comblabla.cngoogle.com The file path of sites.txt is: C:blablaphpsites.txt We use PHP to read the file content line by line. The PHP code is as follows:

The code is as follows	Copy code
$f= fopen("C:blablaphpsites.txt","r"); while (!feof($f)){ $line = fgets($f); echo "site: ",$line," "; } fclose($f);?>

Execute the PHP file and the displayed result returned is:

site: woyouxian.comsite: blabla.cnsite: google.com
The first line of this PHP code opens a file and the last line closes a file. The while loop statement means that when the file does not end, read one line and execute it in a loop until the file pointer reaches the end of the article.

The feof function is a built-in function of PHP, used to test whether the file pointer has reached the end of the file. Returns TRUE if yes, FALSE if not. The English meaning of eof is end of file, which is easy to remember.

Under normal circumstances, the return value of the fgets function is a string. If an error occurs, FALSE is returned.

Describes how to use the PHP built-in function fclose to close a file.

The fclose function syntax is as follows:

fclose(filepointer)
The fclose function returns TRUE if successful and FALSE if failed.

Here is a PHP code example of the fclose function:

The code is as follows

Copy code

代码如下	复制代码
$f = fopen("c:datainfo.txt", "r"); fclose($f); ?>

$f = fopen("c:datainfo.txt", "r");
fclose($f); ?>

In this chapter, we describe how to use fopen, fwrite, and fclose to implement a series of operations of opening files, writing files, and saving and closing files. Focus on the fwrite function.

PHP built-in function fwrite is used to write files.

The common syntax of the fwrite function is:

fwrite(handle,string)

代码如下	复制代码
$f= fopen("C:blablaphpwrite.txt","w"); fwrite($f,"It is awesome.");fclose($f);echo "done"; ?>

Among them, the parameter handle represents the file pointer resource (usually created by the fopen function), and string represents the content to be written.

The following PHP code example demonstrates how to create a new file, write its contents, then save and close the file:

The code is as follows	Copy code
$f= fopen("C:blablaphpwrite.txt","w"); fwrite($f,"It is awesome.");fclose($f);echo "done"; ?>

After executing the PHP file, a file with the path C:blablaphpwrite.txt will be created. The content of the file is It is awesome.

If you want to append content to the existing file, you only need to modify the parameter mode value of fopen, as follows:

$f= fopen("C:blablaphpwrite.txt","a");

For details about the parameter mode value of the fopen function, see fopen.

The fwrite function returns the number of bytes written to the file. If an error occurs, it returns FALSE.

PHP built-in function file_put_contents is used to write files.

代码如下	复制代码
$content = "one for all"; file_put_contents($path,$content); if (file_exists($path))  {echo "ok";}else  {echo "ng";} ?>

The simplest way to write the file_put_contents function can only use two parameters, one is the file path and the other is the content to be written. The syntax is as follows: file_put_contents(filepath,data) If the file does not exist, the file_put_contents function will automatically create the file; if the file already exists, the original file will be overwritten. You can use the file_put_contents function to create and write a new file, or overwrite an original file. Here is an example of PHP code using the file_put_contents function:

The code is as follows	Copy code
$content = "one for all"; file_put_contents($path,$content); if (file_exists($path)) {echo "ok";}else {echo "ng";} ?>

This PHP code example will create a file with the path C:blablafilesysone.txt and the content of the file is one for all.

If you want to append content to an existing file, you can also use the file_put_contents function, just add one parameter.

file_put_contents(filepath,data,flags)
When the value of flags is FILE_APPEND, it means appending content to the existing file.

For example, if we want to append content to the C:blablafilesysone.txt file in the above example, we can write like this:

if (file_exists($path)) {echo "ok";}else {echo "ng";}

The code is as follows

代码如下	复制代码
$path ="C:blablafilesysone.txt"; $content = " all for one"; file_put_contents($path,$content,FILE_APPEND); if (file_exists($path))  {echo "ok";}else  {echo "ng";} ?>

Copy code

$path="C:blablafilesysone.txt";
$content = "all for one"; file_put_contents($path,$content,FILE_APPEND);

?>

After executing the PHP file, we looked at the C:blablafilesysone.txt file and found that the file content had increased and became: one for all all for one The file_put_contents function returns the number of bytes written to the file, or FALSE if an error occurs.

http://www.bkjia.com/PHPjc/629216.html

www.bkjia.com

truehttp: //www.bkjia.com/PHPjc/629216.htmlTechArticleThis article introduces the following common file operation functions file_get_contents Read the entire file content fopen Create and open the file fclose Close the file fgets and read one line of the file file_e...