PHP quirks and pitfalls [closed]

Answer 1

Non-industry-standard operator precedence.

$x = 1;
echo 'foo: ' . $x+1 . ' bar';

Will output: "1 bar", instead of the expected "foo: 2 bar". Solution: Use parenthesis.

Answer 2

Although strings may be iterated using for loops and indexes, they can't be iterated using foreach loops. Example:

$str = 'foo';
$max = strlen($str);

for ($i=0; $i<$max; $i++)  {
    echo $str[$i];
}
// outputs: foo

foreach ($str as $char) {
    echo $char;
}
// Warning: Invalid argument supplied for foreach() ...