Adding code to .txt file without overwriting it - php

Question

<?php
$fn = "content.txt";
if (isset($_POST['content'])){
$content = stripslashes($_POST['content']);
$fp = fopen($fn,"w") or die ("Error opening file in write mode!");
$old_content = file_get_contents($fn);
fputs($fp, $content."\n".$old_content);
fclose($fp) or die ("Error closing file!");
}
?>
<form action="<?php echo $_SERVER["PHP_SELF"] ?>" method="post">
<textarea rows="25" cols="40" name="content"></textarea>
<input type="submit" value="Submit">
</form>
So this is my php code. But it deletes the the previously written data. How do I make it so that the new piece of data is added on a new line? Keeping the last of the data.
Thank you!
<?php
$fn = "content.txt";
if (isset($_POST['content'])){
$content = stripslashes($_POST['content']);
$fp = fopen($fn,"a+") or die ("Error opening file in write mode!");
fputs($fp,$content);
fclose($fp) or die ("Error closing file!");
}
?>
<form action="<?php echo $_SERVER["PHP_SELF"] ?>" method="post">
<textarea rows="25" cols="40" name="content"></textarea>
<input type="submit" value="Submit">
</form>
Now it doesn't work at all

Answer 1

from fopen manual:
'a' Open for writing only; place the file pointer at the end of the
file. If the file does not exist, attempt to create it.
change
$fp = fopen($fn,"w") or die ("Error opening file in write mode!");
to
$fp = fopen($fn,"a") or die ("Error opening file in write mode!");

Answer 2

You can use a or a+ mode instead of w, so you can do:
$fp = fopen($fn,"a") or die ("Error opening file in write mode!");
instead of:
$fp = fopen($fn,"w") or die ("Error opening file in write mode!");
From the manual about fopen mode:
'w': Open for writing only; place the file pointer at the beginning of
the file and truncate the file to zero length. If the file does not
exist, attempt to create it.
'a': Open for writing only; place the file pointer at the end of the
file. If the file does not exist, attempt to create it.
'a+': Open for reading and writing; place the file pointer at the end
of the file. If the file does not exist, attempt to create it.

Answer 3

"Now it doesn't work at all"
^--« As per your edit, this will write each entry on a new line:
I changed:
$content = stripslashes($_POST['content']);
to
$content = stripslashes($_POST['content'] . "\n");
Using \n will have all new entries on a new line.
PHP
<?php
$fn = "content.txt";
if (isset($_POST['content'])){
$content = stripslashes($_POST['content'] . "\n");
$fp = fopen($fn,"a+") or die ("Error opening file in write mode!");
fputs($fp,$content);
fclose($fp) or die ("Error closing file!");
}
?>
<form action="<?php echo $_SERVER["PHP_SELF"] ?>" method="post">
<textarea rows="25" cols="40" name="content"></textarea>
<input type="submit" value="Submit">
</form>
Written to file:
a1
a2
a3
a4
a5
Hello world!!
Testing 123
Written to file one at a time:
a1,a2,a3,a4,a5
Entered in the textarea box as shown and written to file as shown:
Hello world!!
Testing 123
If you want the data to be entered starting from the top, use:
<?php
if (isset($_POST['content'])){
$content = stripslashes($_POST['content'] . "\n");
$file_data = $content;
$file_data .= file_get_contents('content.txt');
file_put_contents('content.txt', $file_data);
}
?>
<form action="<?php echo $_SERVER["PHP_SELF"] ?>" method="post">
<textarea rows="25" cols="40" name="content"></textarea>
<input type="submit" value="Submit">
</form>

Answer 4

Change your call to fopen to use append mode instead of write:
$fp = fopen($fn,"a") or die ("Error opening file in write mode!");
Source: http://www.php.net/manual/en/function.fopen.php

Answer 5

observation - since you were using file_get_contents already I want to mention that there is a reverse function for writing:
file_put_contents($fn, $content, FILE_APPEND);
this way you don't even need to open up the text file and load it into memory.
Helpful for logging too.