PHP Files: What is its importance in PHP

· Dev & Design

There are many built-in functions in PHP to handle files and directories.
Using these functions we can read, write, delete, and get lots of information
of the files.
To perform any funtion on a file we should have the right permission
which will allow us to manupulate that file.

Creating and Deleting a File

We can create a file using the funtion “touch()”. The touch() funtion
when called first searches whether the specified file exists or not
if the file doesnot exists it creates one with the specfied file name.
To delete a file we use the function called “unlink()”. This funtion
removes the file that has been sent as an argument.

touch(�newinfo.txt�); //create a new file, if it doesn�t already exist
unlink(�oldinfo.txt�); //delete a file

Open Existing File

When a file got created, How to access it?
We can access an existing file using the funtion called “fopen()”. This funtion takes
two arguments, The first argument specifies the name of the file that has to be opened,
and the second argument specifies in which mode the file has to be opened.i’e in
“read-r”, “write-w”
or both “read-write” mode.

If the function fopen() executes successfully then it returns an integer value known as
a file pointer. This value should be stored in a variable. This variable is used to work
on with the opened file. If the funtion fopen() fails executing for any reason, It just
returns FALSE. Once the file is used we should close it using the “fclose()” function.
This function takes only the file name as the argument.

$oldfp = fopen(�oldinfo.txt�, �r�); //opens a file for reading
if(!$fp = fopen(�newinfo.txt�, �w�)) //tries to open a file for writing
die(�Error on opening file!�); //terminates the execution of the script if it cannot
open the file

Reading from Files

To read from the file we use the funtion called “fgets()”. When this funtion is
called, it reads out all the characters until a newline(\n), or End Of File(EOF),
or till a specified length is reached.

The function “fgets()” is similar to “fgets()”, Unlike fgets() it returns
a single character from a file. there is no need to specify any length as a argument,
since a character is always 1 byte.

$text = fgets($fp, 2000); //reads 2000 bytes at most
$chr = fgetc($fp); //reads 1 byte only

More File Handling Functions

There are a lot of other functions that you can use with files like: testing functions
� �file_exists()�, �is_file()�, �is_dir()�, �is_readable()�, �is_writeable()�,
�is_executable()�; functions that return information on files: �filesize()�,
�fileatime()�, �filemtime()�, �filectime()�. You can figure out what the function
does by just reading its name.

Following table contains few File Handling functions and
their description

Example Description Preview
chdir Changes PHP’s current directory
to specified directory. Returns TRUE on success or FALSE on failure.
chroot Change the root directory  
closedir Closes a directory handle
previously opened with opendir(). 
copy Makes a copy of a file. Returns
TRUE if the copy succeeded, FALSE otherwise.  
dir dir — directory class class dir
{ dir(string directory); string path; resource handl… 
file Returns the contents of a file in
an array. 
filesize Gets file size  
fopen Opens a file handle to be used
fread Reads the contents of a file
descriptor assigned with fopen(). 
fwrite Writes to a file descriptor
opened with fopen(). 
getcwd gets the
current working directory string. getcwd (void) Returns the current
working directory.  
opendir Returns a directory handle that
can be used with readdir(), closedir() and rewinddir(). 
readdir Reads the next file from a
directory handle opened with opendir(). 
rename Renames a file from the old file
name to the new file name.  
rewinddir rewind directory handle, void rewinddir ( resource dir_handle) Resets the
directory stream indicated by dir_handle to the beginning of the
scandir List
files and directories inside the specified path  
Unlink Deletes a file. 

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