Wednesday, July 7, 2010

PHP File Handling

The fopen() function is used to open files in PHP.



Opening a File


The fopen() function is used to open files in PHP.

The first parameter of this function contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened:









$file=fopen("welcome.txt","r");
?>




The file may be opened in one of the following modes:







































ModesDescription
rRead only. Starts at the beginning of the file
r+Read/Write. Starts at the beginning of the file
wWrite only. Opens and clears the contents of file; or creates a new file if it doesn't exist
w+Read/Write. Opens and clears the contents of file; or creates a new file if it doesn't exist
aAppend. Opens and writes to the end of the file or creates a new file if it doesn't exist
a+Read/Append. Preserves file content by writing to the end of the file
xWrite only. Creates a new file. Returns FALSE and an error if file already exists
x+Read/Write. Creates a new file. Returns FALSE and an error if file already exists

Note: If the fopen() function is unable to open the
specified file, it returns 0 (false).

Example


The following example generates a message if the fopen() function is unable
to open the specified file:









$file=fopen("welcome.txt","r") or exit("Unable to open file!");
?>






Closing a File


The fclose() function is used to close an open file:







$file = fopen("test.txt","r");

//some code to be executed

fclose($file);
?>




Check End-of-file


The feof() function checks if the "end-of-file" (EOF) has been reached.

The feof() function is useful for looping through data of unknown length.

Note: You cannot read from files opened in w, a, and x mode!







if (feof($file)) echo "End of file";




Reading a File Line by Line


The fgets() function is used to read a single line from a file.

Note: After a call to this function the file pointer has moved to the next line.

Example


The example below reads a file line by line, until the end of file is reached:







$file = fopen("welcome.txt", "r") or exit("Unable to open file!");
//Output a line of the file until the end is reached
while(!feof($file))
{
echo fgets($file). "
";
}
fclose($file);
?>




Reading a File Character by Character


The fgetc() function is used to read a single character from a file.

Note: After a call to this function the file pointer moves to the next character.

Example


The example below reads a file character by character, until the end of file is reached:







$file=fopen("welcome.txt","r") or exit("Unable to open file!");
while (!feof($file))
{
echo fgetc($file);
}
fclose($file);
?>

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