understanding nested ternary operators [duplicate] - php

Question

This question already has answers here:
Stacking Multiple Ternary Operators in PHP
(11 answers)
Closed 2 years ago.
I have this piece of code that is unclear to me, specifically the complex use of the ternary
operators
if (!$byField && is_numeric($v)){ // by ID
$r=$fromRow?
$fromRow:
($v?
dbRow("select * from pages where id=$v limit 1"):
array()
);
}
if someone could explain how to evaluate the nested use of ternary operators

Answer 1

Using nested ternary operators in your code adds unnecessary complexity. For the same reason, it should not be used. Just use a normal if-else block instead. That's far more readable.
if (condition) {
# code...
}
else {
# code...
}
To answer your question:
$r = $fromRow ? $fromRow : ( $v ? dbRow("..."): array() );
The above statement can be rewrote as follows:
if (!$byField && is_numeric($v))
{
if ($fromRow)
{
$r = $fromRow;
}
elseif ($v)
{
$r = dbRow("select * from pages where id=$v limit 1"):
}
else
{
$r = array();
}
}
As you can see, it's more readable.

Answer 2

Consider the following code:
<?php
$a = true;
$b = false;
$c = true;
echo (
$a
? 'A is true'
: (
$b
? 'A is false, but B is true'
: (
$c
? 'A is false, B is false, but C is true'
: 'A, B and C are all false'
)
)
);
?>
Which could easily be rewritten as so:
<?php
if ($a) {
echo 'A is true';
} else {
if ($b) {
echo 'A is false, but B is true';
} else {
if ($c) {
echo 'A is false, B is false but C is true';
} else {
echo 'A, B and C are all false';
}
}
}
?>

Answer 3

if (!$byField && is_numeric($v)){ // by ID
if ($fromRow) {
$r = $fromRow;
else if ($v) {
$r = dbRow("select * from pages where id=$v limit 1"):
} else {
$r = array();
}
}