Remove the last character from a string

Contrary to the question asked, rtrim() will remove any number of characters, listed in the second argument, from the end of the string. In case you expect just a single comma, the following code would do:

$newarraynama = rtrim($arraynama, ",");

But in my case I had 2 characters, a comma and a space, so I had to change to

$newarraynama = rtrim($arraynama, " ,");

and now it would remove all commas and spaces from the end of the string, returning a, b, c, d, e either from a, b, c, d, e,, a, b, c, d, e,,,, a, b, c, d, e, or a, b, c, d, e , ,, , ,

But in case there could be multiple commas but you need to remove only the last one, then rtrim() shouldn't be used at all - see other answers for the solution that directly answers the question.

However, rtrim() could be a good choice if you don't know whether the extra character could be present or not. Unlike substr-based solutions it will return a, b, c, d, e from a, b, c, d, e

You can use substr:

echo substr('a,b,c,d,e,', 0, -1);
# => 'a,b,c,d,e'

In case the last character could be multi-byte, then mb_substr() should be used instead.

An alternative to substr is the following, as a function:

substr_replace($string, "", -1)

Is it the fastest? I don't know, but I'm willing to bet these alternatives are all so fast that it just doesn't matter.

Note that this function is not multibyte-safe, and will produce the undesired result if the last character will happen to be a multi-byte one.

You can use

substr(string $string, int $start, int[optional] $length=null);

See substr in the PHP documentation. It returns part of a string.

Use the regular expression end of string anchor "$"

$string = preg_replace("/,$/", '', $string);

"The fastest best code is the code that doesn't exist".

Speaking of edge cases, there is a quite common issue with the trailing comma that appears after the loop, like

$str = '';
foreach ($array as $value) {
    $str .= "$value,";
}

which, I suppose, also could be the case in the initial question. In this case, the fastest method definitely would be not to add the trailing comma at all:

$str = '';
foreach ($array as $value) {
    $str .= $str ? "," : "";
    $str .= $value;
}

here we are checking whether $str has any value already, and if so - adding a comma before the next item, thus having no extra commas in the result.