These questions must not be made during the interview! ! !
1. Test whether the array is empty before looping
$items = [];
// ...
if (count($items) > 0) {
foreach ($items as $item) {
// process on $item ...
}
}
foreach and array functions (array_*) can handle empty arrays.
No need to test first
Can reduce one level of indentation
$items = [];
// ...
foreach ($items as $item) {
// process on $item ...
}
2. Encapsulate the code content into an if statement summary
function foo(User $user) {
if (!$user->isDisabled()) {
// ...
// long process
// ...
}
}
This is not unique to PHP, but I often encounter such situations. You can reduce the indentation by returning early.
All main methods are at the first indentation level
function foo(User $user) {
if ($user->isDisabled()) {
return;
}
// ...
// 其他代码
// ...
}
Three, call the isset method multiple times
You may encounter the following situations:
$a = null;
$b = null;
$c = null;
// ...
if (!isset($a) || !isset($b) || !isset($c)) {
throw new Exception("undefined variable");
}
// 或者
if (isset($a) && isset($b) && isset($c) {
// process with $a, $b et $c
}
// 或者
$items = [];
//...
if (isset($items['user']) && isset($items['user']['id']) {
// process with $items['user']['id']
}
We often need to check whether a variable is defined. PHP provides the isset function to detect the variable, and the function can accept multiple parameters at once, so the following code may be better:
$a = null;
$b = null;
$c = null;
// ...
if (!isset($a, $b, $c)) {
throw new Exception("undefined variable");
}
// 或者
if (isset($a, $b, $c)) {
// process with $a, $b et $c
}
// 或者
$items = [];
//...
if (isset($items['user'], $items['user']['id'])) {
// process with $items['user']['id']
}
Four, echo and sprintf methods used together
$name = "John Doe";
echo sprintf('Bonjour %s', $name);
This code may be smiling, but I happened to write it for a while. And I still see a lot! Instead of combining echo and sprintf, we can simply use the printf method.
$name = "John Doe";
printf('Bonjour %s', $name);
Five, check whether there is a key in the array by combining the two methods
$items = [
'one_key' => 'John',
'search_key' => 'Jane',
];
if (in_array('search_key', array_keys($items))) {
// process
}
The last mistake I often see is the combined use of in_array and array_keys. All of these can be replaced with array_key_exists.
$items = [
'one_key' => 'John',
'search_key' => 'Jane',
];
if (array_key_exists('search_key', $items)) {
// process
}
We can also use isset to check whether the value is not null.
if (isset($items['search_key'])) {
// process
}
Pay attention, don't get lost
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