Foreach loop, but for first key do something else - php

Question

Sorry if this is confusing. It's tough for me to put into words having beginner knowledge of PHP.
I'm using the following foreach loop:
foreach ($_POST['technologies'] as $technologies){
echo ", " . $technologies;
}
Which produces:
, First, Second, Third
What I want:
First, Second, Third
All I need is for the loop to skip the echo ", " for the first key. How can I accomplish that?

Answer 1

You can pull out the indices of each array item using => and not print a comma for the first item:
foreach ($_POST['technologies'] as $i => $technologies) {
if ($i > 0) {
echo ", ";
}
echo $technologies;
}
Or, even easier, you can use implode($glue, $pieces), which "returns a string containing a string representation of all the array elements in the same order, with the glue string between each element":
echo implode(", ", $_POST['technologies']);

Answer 2

For general case of doing something in every but first iteration of foreach loop:
$first = true;
foreach ($_POST['technologies'] as $technologies){
if(!$first) {
echo ", ";
} else {
$first = false;
}
echo $technologies;
}
but implode() is best way to deal with this specific problem of yours:
echo implode(", ", $_POST['technologies']);

Answer 3

You need some kind of a flag:
$i = 1;
foreach ($_POST['technologies'] as $technologies){
if($i > 1){
echo ", " . $technologies;
} else {
echo $technologies;
}
$i++;
}

Answer 4

Adding an answer that deals with all types of arrays using whatever the first key of the array is:
# get the first key in array using the current iteration of array_keys (a.k.a first)
$firstKey = current(array_keys($array));
foreach ($array as $key => $value)
{
# if current $key !== $firstKey, prepend the ,
echo ($key !== $firstKey ? ', ' : ''). $value;
}
demo

Answer 5

Why don't you simply use PHP builtin function implode() to do this more easily and with less code?
Like this:
<?php
$a = ["first","second","third"];
echo implode($a, ", ");
So as per your case, simply do this:
echo implode($_POST['technologies'], ", ");