PHP prevent extra empty line when writing text to file - php

Question

I'm having a small issue regarding a foreach() loop and writing an array to a text file within.
The loop gives me the format in the file that I want but it also adds (as I was told) an unwanted empty line at the end of the file.
Here is my piece of code:
foreach($data_arr as $data => $input)
{ fwrite($fh, $data . ":" . $input . "\n") or die("something went wrong here"); }
Is there a way to prevent this from happening and not add the \n when it reaches the end of the array?

Answer 1

You can do something like this :
$data_array = ['c', 'h', "hf"];
$last = count($data_array) - 1; #size of the array
foreach($data_array as $data => $input)
{
$separator = $data == $last ? "" : "\n"; #if is last, then seperator isn't a back to line
fwrite($fh, $data . ":" . $input . $separator);
}

Answer 2

Just check if current index is the last one, then eventually add "\n" to the string
$last_index = count($data_arr)-1;
foreach ($data_arr as $data => $input)
{
$string = $data . ":" . $input;
if ($data != $last_index)
{
$string .= "\n";
}
fwrite($fh, $string) or die("something went wrong here");
}

Answer 3

Determining whether you are doing something for the last time, is cumbersome - for starters, you need to count your items, and then you need a loop index to compare to that count …
Much easier to determine, whether you are doing something for the first time. So just reverse your logic here - do not try to output “all lines, followed by a newline each, except the last one”, but instead, output “all lines preceded by a newline each, except the first one.”
You could use a simple boolean flag for that:
$is_first_line = true;
foreach($data_arr as $data => $input) {
fwrite($fh, ($is_first_line ? "" : "\n") . $data . ":" . $input);
$is_first_line = false;
}
Or you just append a variable before the line data all the time - and simply make that variable “empty” on the first iteration, and then fill it with a newline character for all the following ones:
$prefix = "";
foreach($data_arr as $data => $input) {
fwrite($fh, $prefix . $data . ":" . $input);
$prefix = "\n";
}