PHP file operation basic code

PHP provides a series of I/O functions that can easily implement the functions we need, including file system operations and directory operations (such as "copy"). Below, the editor of Brothers in Arms PHP Training

will introduce to you the basic file reading and writing operations: (1) Read files

; (2)
Write files; (3) Append to files.

　The following is an article about basic file reading and writing operations. I once learned the basic file operations after reading this article. I post it here to share with you:

　Reading files:

　PHP code:

1.
　 2.

3. $file_name ="data.dat";

4. // Absolute path of the file to be read: homedata.dat

5.

6. $file_pointer =fopen($file_name, "r");

　7. // Open the file, 8. "r" is a mode, 9. Or the operation method we want to perform, 10. See the introduction later in this article for details

　 11.

12. $file_read =fread($file_pointer, filesize($file_name));

13. // Read the file content through the file pointer

15.

16. fclose($file_pointer ; .

　Write file:

　PHP code:

　1. .​

　　6. $file_pointer =fopen($file_name, "w");

　7. // "w" is a mode, 8. See below for details

　9.

　10. fwrite($file_pointer, "what you wanna write");

　11. // First cut the file 12. to 0 bytes, 13. Then write

　14.
　15. fclose($file_pointer);

　16. // End

　 17.

18. print "Data successfully written to file";

19.

20. ?>

21. Append to the end of the file:

PHP code:

　1.
　 2.

3. $file_name ="data.dat";

4. // Absolute path: homedata.dat

5.

6. $file_pointer =fopen($file_name, "a ");

　 7. // "w" mode

8.

9. fwrite($file_pointer,"what you wanna append");

10. // No 11. Cut the file 12. into 0 bytes, 13. Append data to the end of the file

14.

15. fclose($file_pointer);
16. // End

17.

18. print "Data appended to file successfully";

　 19.

20. ?>

21.

The above is just a brief introduction, below we will discuss some deeper ones.

　 Sometimes multiple people write (most commonly on websites with large traffic), which will produce useless data written to the file, for example:

　 The content of the info.file file is as follows ->

　 |1| Mukul|15|Male|India (n)

　|2|Linus|31|Male|Finland(n)

Now two people are registered at the same time, causing file damage->

　info.file ->

　|1| Mukul|15|Male|India

　|2|Linus|31|Male|Finland

　 |3|Rob|27|Male|USA|

　Bill|29|Male|USA

　 In the above example, when PHP writes When Rob's information entered the file, Bill also started writing. At this time, 'n' recorded by Rob needed to be written, causing the file to be damaged.

We certainly don’t want this to happen, so let’s look at file locking:

PHP code:

1.
2.

3. $file_name ="data.dat";

4.

　 5. $file_pointer =fopen($file_name, "r");

6.

7. $lock =flock($file_pointer, LOCK_SH);

8. // I use 4.0.2, 9. So use LOCK_SH, 10. You may need to write directly 1.

　 11.

　 12. if ($lock) {

　 13.

14. $file_read =fread($file_pointer, filesize($file_name) ;19. }

　 20.

21. fclose($file_pointer);

22.

23. print "The file content is $file_read";
　26.

In the above example, if both files read.php and read2.php have to access the file, then they can both read it, but when a program needs to write, it must wait until the read operation is completed and the file is freed.

　 PHP code:

1.
2.

3. $file_name ="data.dat"; ... lock) {
　 12.

13. fwrite($file_pointer,"what u wanna write");

　 14. flock($file_pointer,LOCK_UN);

15. // If the version is lower than PHP4.0.2, 16. Use 3 instead of LOCK_UN

　 17.

18. }

19.

20. fclose($file_pointer);

21.

22. print "Data written to file successfully";

　23.

　 24. ?>

25.

Although the "w" mode is used to overwrite files, I don't think it is suitable.

　 PHP code:

1.
2.

3. $file_name ="data.dat"; ... lock) {

　 12.

13. fseek($file_pointer, 0,SEEK_END);

　 14. // If the version is smaller than PHP4.0RC1, 15. use fseek($file_pointer, filsize($file_name));

　 16.

　 17. fwrite($file_pointer,"what u wanna write");

　 18. flock($file_pointer,LOCK_UN);

　 19. // If the version is lower than PHP4.0.2, 20. Use 3 Replace LOCK_UN
　 21.

22. }

23.

24. fclose($file_pointer); 25.

26. print "Data written to file successfully";

27.

28. ?>

　　29.

　Hmmm..., Appending data is a little different from other operations, that is FSEEK! It is always a good habit to confirm that the file pointer is at the end of the file.

　If it is under Windows system, the above file needs to be preceded by ''.

　FLOCK Miscellaneous Talk:

　Flock() only locks the file after it is opened. In the above column, the file is locked after it is opened. Now the content of the file is only the content at that time, and does not reflect the results of other program operations. Therefore, fseek should be used not only for file append operations, but also for read operations.

　(The translation here may not be very accurate, but I think I get the idea).

　 About the mode:

　 'r' - open in read-only mode, the file pointer is placed at the file header

　 'r+' - open in read-write mode, the file pointer is placed at the file header

'w' - open for write-only, the file The pointer is placed at the file header, and the file is cut to 0 bytes. If the file does not exist, try to create the file

　　'w+' - Open for reading and writing, the file pointer is placed at the file header, and the file size is cut to 0 bytes. If the file does not exist, try to create the file

　 'a' - Open for writing only, the file pointer is placed at the end of the file. If the file does not exist, try to create the file

　 'a+' - Open for reading and writing, the file pointer is placed at the end of the file , if the file does not exist, try to create the file

　By the way, the code to create the file directory

　 //Create a directory similar to "../../../xxx/xxx.txt"

　 function createdirs($path ,$mode = 0777) //mode 077

　{

　 $dirs = explode('/',$path);

　$pos = strrpos($path,".");

　 if ($pos = == false) { //note: three equal signs

　 // not found, means pathends in a dir not file

　 $subamount=0;

　}

　 else {

　 $subamount=1;

　

　for ($c=0;$c
$thispath="";

　for ($cc=0; $cc
　$thispath.=$dirs[$cc].'/';

　}

　if( !file_exists($thispath)) {

　　　//print "$thispath

　";

　mkdir($thispath,$mode);//mkdir function creates directory

　　}

　　}

　// Calls such as createdirs("xxx/xxxx/xxxx",);

　 // $GLOBALS["dirseparator"] was used in the original function and I changed it to '/'

　 functionrecur_mkdirs($path, $mode = 0777) // mode 0777

　{

　　 //$GLOBALS["dirseparator"]

　 $dirs =explode($GLOBALS["dirseparator"],$path);

　$pos = strrpos($path,".");

　if ($pos === false) { //note: three equal signs

　 // not found, means pathends in a dir not file

　$subamount=0;

　}

　 else {

　　$ subamount=1;

　}

　These are just some basic file operation codes. I believe they are very useful for beginners. I post them here, hoping to inspire others!