老天尊的死期: PHP常見問題

取某段字串裡的數字
preg_match_all('!\d+!', $str, $matches);
取某段字串裡的日期 (我們假設日期格式是 YYYY-MM-DD HH-ii-ss)
preg_match('/^\d{4}-\d{2}-\d{2}\s\d{2}:\d{2}:\d{2}/', $str, $matches);
去除前後的空白
$ php -r '$str = " hello world "; echo trim($str);'
hello world
參考資料：
http://stackoverflow.com/questions/6278296/extract-numbers-from-a-string

去除陣列所有字串前後的空白
http://stackoverflow.com/questions/6769464/how-can-i-trim-all-strings-in-an-array
使用array_map()
$source_array = array(" hey ", "bla ", " test");
$result = array_map('trim', $source_array); // $result = array("hey", "bla", "test");

開發時在網頁上顯示錯誤
編輯/etc/php5/apache2/php.ini 修改以下設定
error_reporting = E_ALL
display_errors = On
( nginx+fpm )
If you have /etc/php5/fpm/php.ini (used in Debian, Ubuntu style config) then changes to this file should take effect, and that configuration may be further overridden per pool by making changes to specific /etc/php5/fpm/pool.d/*.conf files.
如果你有 /etc/php5/fpm/php.ini （Debian, ubuntu），則編輯修改以下設定即可（採用）
; enable display of errors
display_errors = On
display_startup_errors = On
而該設定會被 /etc/php5/fpm/pool.d/*.conf 的設定覆蓋，例 ( /etc/php5/fpm/pool.d/www.conf )：
; enable display of errors
php_flag[display_errors] = on
php_flag[display_startup_errors] = on

註：
; Production Value: E_ALL & ~E_DEPRECATED & ~E_STRICT =>產品上線用
; Development Value: E_ALL => 開發用
參考資料：
http://stackoverflow.com/questions/5680831/php-does-not-display-error-messages
http://stackoverflow.com/questions/13929314/display-errors-for-php5-fpm-not-working-with-nginx display_errors for php5-fpm not working with nginx

在PHP腳本中修改錯誤輸出的級別
error_reporting(0); // Turn off all error reporting
error_reporting(E_ALL ^ E_NOTICE); // Report all errors except E_NOTICE, This is the default value set in php.ini
http://stackoverflow.com/questions/2867057/how-do-i-turn-off-php-notices

file_put_contents的LOCK_EX 參數
在php.net中，file_put_contens的描述是
int file_put_contents ( string $filename , mixed $data [, int $flags = 0 [, resource $context ]] )
而地三個參數$flags常用的有：
FILE_APPEND=>直接在該檔已有的內容後面追加內容
LOCK_EX=>寫檔的時候先鎖定，防止多人同時寫入造成內容丟失
當需要頻繁操作file_put_contents函數寫txt檔時，經常出現前半截內容缺失的情況，非常苦惱。此時LOCK_EX非常有用，加上它之後，再也沒有出現過內容缺失的情況了。LOCK_EX的意思很直白，就是寫檔時，先鎖上這個檔，這樣只允許某個客戶端訪問的時候寫，其他客戶端訪問不能寫了。
http://www.wyxuan.com/184.html PHP写文件函数file_put_contents确实给力

unlink()函數
unlink() 函数删除文件。若成功，则返回 true，失败则返回 false。
Ex.
$ touch test2
$ ls
smarty test test2
$ php -r 'unlink("test2");'
$ ls
smarty test

php的refrence符号&用法
& 可以當二位元AND運算也可以當reference，以下為reference的例子

$arr = array(1, 2, 3);
function a(&$arr2){
 foreach ($arr2 as &$value) {
  $value = $value*$value;
 }
 echo '$arr2:';
 print_r($arr2);
 // print_r($arr); // Notice: Undefined variable: arr
}
a($arr);
echo '<br>$arr:';
print_r($arr);
// print_r($arr2); // Notice: Undefined variable: arr2
// a(&$arr); // Fatal error: Call-time pass-by-reference has been removed => And as of PHP 5.4.0( PHP Version 5.6.8 on my server ), call-time pass-by-reference was removed, so using it will raise a fatal error.

輸出：
$arr2:Array ( [0] => 1 [1] => 4 [2] => 9 )
$arr:Array ( [0] => 1 [1] => 4 [2] => 9 )

如果a(&$arr)這樣呼叫，在PHP5.3.0會產生警告，在PHP5.4.0+會產生fatal error.

以純變數為例子：

$a='小妹哥';
$b=$a;
$c=&$a;
$b='大妹哥';
$c='拉屎小妹哥';
echo $a;

輸出：
拉屎小妹哥

傳值呼叫（call By Value） - 將變數的值傳入函數，並不會更變原來的值
傳址呼叫（call By Reference） - 將變數實際儲存的位址傳入，在函數變更參數值，也會同時更變傳入的變數值

參考資料：
http://stackoverflow.com/questions/3737139/reference-what-does-this-symbol-mean-in-php Reference - What does this symbol mean in PHP?
http://www.php.net/manual/en/language.references.php References Explained
http://php.net/manual/en/language.references.pass.php Passing by Reference
http://syunguo.blogspot.com/2013/04/php_1.html [PHP]傳址與傳值呼叫

array_chunk()
http://w3school.com.cn/php/func_array_chunk.asp
把array分割，chunk=>大塊的意思
Ex.
preserve_key = true - 保留原始数组中的键名
$ php -r '$a=array("a"=>"Cat","b"=>"Dog","c"=>"Horse"); print_r(array_chunk($a,2,true));'
Array
(
[0] => Array
(
[a] => Cat
[b] => Dog
)

[1] => Array
(
[c] => Horse
)

)

$ php -r '$a=array("a"=>"Cat","b"=>"Dog","c"=>"Horse","d"=>"Cow"); print_r(array_chunk($a,2));'
Array
(
[0] => Array
(
[0] => Cat
[1] => Dog
)

[1] => Array
(
[0] => Horse
[1] => Cow
)

)

array_slice()
http://www.w3school.com.cn/php/func_array_slice.asp
陣列中根據條件取出一段值，並返回
Ex.
從第二個開始往後取兩個
$ php -r '$a=array("e"=>"Cat","b"=>"Dog","c"=>"Horse","d"=>"Cow"); print_r(array_slice($a,1,2));'
Array
(
[b] => Dog
[c] => Horse
)
從倒數第二個（與key的升降冪無關）開始往後取兩個
$ php -r '$a=array(5=>"Cat",1=>"Dog",2=>"Horse",3=>"Cow"); print_r(array_slice($a,-2,2));'
Array
(
[0] => Horse
[1] => Cow
)
preserve = true，數字型key保留鍵值
$ php -r '$a=array(5=>"Cat",1=>"Dog",2=>"Horse",3=>"Cow"); print_r(array_slice($a,-2,2,true));'
Array
(
[2] => Horse
[3] => Cow
)

字串轉unicdoe，unicode轉字串
http://stackoverflow.com/questions/7106470/utf-8-to-unicode-code-points

function unicode2utf8($str){
    if(!$str) return $str;
    $decode = json_decode($str);
    if($decode) return $decode;
    $str = '["' . $str . '"]';
    $decode = json_decode($str);
    if(count($decode) == 1){
            return $decode[0];
    }
    return $str;
}
echo json_encode('測試'); // \u6e2c\u8a66

echo "
unicode2utf8('\u6e2c\u8a66'):".unicode2utf8('\u6e2c\u8a66'); // 測試

s

快速檢查必填欄位有無缺失（無法判斷是缺哪個欄位）
http://stackoverflow.com/questions/13169588/how-to-check-if-multiple-array-keys-exists

//The values in this arrays contains the names of the indexes (keys) that should exist in the data array
$required = array('key1', 'key2', 'key3' );

$data = array(
    'key1' => 10,
    'key2' => 20,
    'key3' => 30,
    'key4' => 40
);

if(count(array_intersect_key(array_flip($required), $data)) === count($required)) {
    //All required keys exist!              
}

過濾掉不合法的欄位
http://stackoverflow.com/questions/4260086/php-how-to-use-array-filter-to-filter-array-keys
$my_array = array("foo" => 1, "hello" => "world");
$allowed = array("foo", "bar");
$inserted_data = array_intersect_key($my_array, array_flip($allowed)); // array("foo" => 1);

計算生肖
https://en.wikipedia.org/wiki/Chinese_zodiac
必須把每年除夕的日子存起來，再另外處理。最後我只用國曆做簡單的判斷

PHP多維陣列搜尋（由值找key）
http://stackoverflow.com/questions/8102221/php-multidimensional-array-searching-find-key-by-specific-value

function search($columns, $field, $value){
    foreach ($columns as $key => $column) {
        if ($column[$field] === $value) {
            return $key;
        }
    }
    return false;
}

$products = array (
1  => array(
        'shortname'     => 'The One-Touch Tea Maker',
        'price'         => '249.99',
        ),

2  => array(
        'shortname'     => 'Variable Temperature Kettle',
        'price'         => '129.99',
        ),
);

$key = search($products, 'shortname', 'Variable Temperature Kettle');
echo "\$key:".$key;

輸出：
$key:2
(找$porducts 中 shortname為 Variable Temperature Kettle 的key值(通常為id))

備份上傳的檔案（框架以ThinkPHP為例）
http://www.w3school.com.cn/php/func_filesystem_copy.asp

$project_path =pathinfo(THINK_PATH, PATHINFO_DIRNAME);
$import_path = $project_path."/Uploads/import";
$file_name = "import-".microtime(true)."-".$_FILES['excel']['name'];
$file_full_path = $import_path."/".$file_name;
copy($_FILES['excel']['tmp_name'],$file_full_path);

注意：
input[type=file]的name記得要寫$_FILES['excel']['tmp_name']，不然抓不到檔案會複製不出結果

從陣列的值求其key
http://stackoverflow.com/questions/8729410/php-get-key-name-of-array-value

$arr = array ('first' => 'a', 'second' => 'b', );
$key = array_search ('a', $arr); // $key = 'first'

array_search()可以從值反查key

避免PHP Deprecated: preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead in xxx.php on line xx錯誤
http://stackoverflow.com/questions/2082207/calling-function-inside-preg-replace-thats-inside-a-function calling function inside preg_replace thats inside a function
http://stackoverflow.com/questions/21334934/deprecated-preg-replace-the-e-modifier-is-deprecated-use-preg-replace-call Deprecated: preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead in
http://stackoverflow.com/questions/20951133/deprecated-preg-replace-how-to-convert-to-preg-replace-callback Deprecated: preg_replace(): How to convert to preg_replace_callback?
直接看程式

error_reporting(E_ALL);

function embed_video($url) {
 echo "\n\$url:".$url;
    return $url;
}

$result = "[video]http://youtube.com/id/xxxxxxpron[/video]";
$result = preg_replace(
    "/\[video\](.+?)\[\/video\]/e",
    "embed_video('$1')",
    $result
);
echo "\n\$result:" . $result."\n";

$result2 = "[video]http://youtube.com/id/xxxxxxpron[/video]";
$result2 = preg_replace_callback(
    "/\[video\](.+?)\[\/video\]/",
    function($matches) {
     print_r($matches);
        return embed_video($matches[1]);
    },
    $result2
);
echo "\n\$result2:" . $result2;

結果：
PHP Deprecated: preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead in xx.php on line 14
$url:http://youtube.com/id/xxxxxxpron
$result:http://youtube.com/id/xxxxxxpron
Array
(
[0] => [video]http://youtube.com/id/xxxxxxpron[/video]
[1] => http://youtube.com/id/xxxxxxpron
)
$url:http://youtube.com/id/xxxxxxpron
$result2:http://youtube.com/id/xxxxxxpron

注意：
改成preg_replace_callback後，第一個參數 $pattern ( "/\[video\](.+?)\[\/video\]/e" )，必須把替換操作符的 /e ( 替換字符串作為表達式 ) 拿掉，否則會報錯
PHP Warning: preg_replace_callback(): Modifier /e cannot be used with replacement callback in xx.php on line xx
Don't use the \e modifier in your preg_replace_callback() call or php will throw the following warning and return nothing
不要使用 modifier 在 preg_replace_callback() 呼叫，否則php會丟警告且返回空值

較簡單的範例

error_reporting(E_ALL);

$x = 'abcd-efg-hijk-lmnop';

$x = preg_replace(
    '/-(.)/e', //pattern
    "strtoupper('$1')",
    $x //subject
);

echo "\n\$x:" . $x . "\n"; //abcdEfgHijkLmnop

$x = 'abcd-efg-hijk-lmnop';

$x = preg_replace_callback(
    '/-(.)/', //pattern
    function ($matches) {
        //callback
        print_r($matches);
        return strtoupper($matches[1]);
    },
    $x //subject
);

echo "\n\$x:" . $x; //abcdEfgHijkLmnop

結果：
PHP Deprecated: preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead in xx.php on line 10

$x:abcdEfgHijkLmnop
Array
(
[0] => -e
[1] => e
)
Array
(
[0] => -h
[1] => h
)
Array
(
[0] => -l
[1] => l
)

$x:abcdEfgHijkLmnop

避免PHP Strict Standards: Only variables should be passed by reference in strict_standards.php on line xx錯誤
http://stackoverflow.com/questions/9848295/strict-standards-only-variables-should-be-passed-by-reference-error “Strict Standards: Only variables should be passed by reference” error
直接看程式

error_reporting(E_ALL);
$value = "a.b.c.d";
$extension = strtolower(array_pop(explode(".", $value)));
print_r($extension);

結果：
PHP Strict Standards: Only variables should be passed by reference in /home/ds/strict_standards.php on line 6
d

解法：
把explode()放到外面處理，多一行

error_reporting(E_ALL);
$value = "a.b.c.d";
$explodes = explode(".", $value);
$extension = strtolower(array_pop($explodes));
print_r($extension);

結果：
d
( PHP Strict Standards 錯誤沒了 )

檢查class有無方法和在一行中if兩次
http://stackoverflow.com/questions/10287789/check-if-class-has-method-in-php
$where = (method_exists($Model, "get_where")) ? $Model->get_where() : ( (isset($this->_map['where']))? $this->_map['where'] : null );
1. 使用 method_exists($Class, "method_name") 檢查
2. 在一行中使用兩次if：$result = ( condition1 ) ? a : ( ( condition2 )? b : c );

得到陣列中最後一個key
http://stackoverflow.com/questions/2348205/how-to-get-last-key-in-an-array
$array = array(
'first' => 123,
'second' => 456,
'last' => 789,
);
end($array); // move the internal pointer to the end of the array
$key = key($array); // fetches the key of the element pointed to by the internal pointer
echo $key; // last, 但$array的順序是不變的

使用sprintf連結字串
http://www.w3school.com.cn/php/func_string_sprintf.asp
喇叭王：要組合字串都改用sprintf，考量之後維護的人的關係。今天要是這字串比較長超過一個畫面你在維護的時候怎麼知道裡面有幾個變數你能保證不會看漏嗎
例：

$a = "Daniel";
$b = "Lin";
$c = "Laba King";
$text = sprintf("%s %s, %s",
    $a,
    $b,
    $c
);
echo $text."\n";
$text2 = $a." ".
    $b.", ".
    $c;

echo $text2;

結果：
Daniel Lin, Laba King
Daniel Lin, Laba King
結果是一樣的，看起來用sprintf()好像比較好

XML字串轉陣列
http://stackoverflow.com/questions/12148662/xml-to-array-php
使用json_decode(json_encode(simplexml_load_string($xml)),TRUE)

$s =<<<EOS
<root>
<Formula>
<formulaname>Basic</formulaname>
<movespeed>1</movespeed>
<box>4</box>
<chicken>3</chicken>
<ducks>1</ducks>
<cereal>2</cereal>
</Formula>
</root>
EOS;
$array = json_decode(json_encode(simplexml_load_string($s)),TRUE);
echo "<pre>\$array:";
print_r($array);
echo "</pre>";

結果：
$array:Array
(
[Formula] => Array
(
[formulaname] => Basic
[movespeed] => 1
[box] => 4
[chicken] => 3
[ducks] => 1
[cereal] => 2
)
)

in_array() 的BUG
https://stackoverflow.com/questions/7669589/in-array-does-not-work-as-expected
in_array('string', [1,0]) // true，因為 0 == "string"為true
in_array('string', [1,0], true) // false. working as expected

兩個變數中的＆
https://stackoverflow.com/questions/22376222/what-does-a-single-ampersand-operator-do-in-php
What does a single ampersand ('&') operator do in PHP?
這是bitwise operator AND
ex.
$a = 9;
$b = 10;
echo $a & $b;

place value 128 64 32 16 8 4 2 1
$a 0 0 0 0 1 0 0 1 =9
$b 0 0 0 0 1 0 1 0 =10

result 8

使用microtime(true)計算php程序代碼執行消耗時間
https://blog.csdn.net/eflyq/article/details/19130141
https://stackoverflow.com/questions/33107182/php-microtime-is-correct
$start = microtime(true);
// code
$time_elapsed_secs = microtime(true) - $start; // code執行了多少「秒」

laravel判斷model的特定欄位是否被更改

https://stackoverflow.com/a/28866535 Laravel Eloquent update just if changes have been made

https://stackoverflow.com/a/40544518 How to search if the key value in an array exists in another array, using PHP?

$dirty = $user->getDirty();
$columns = [
    'phone', 'address',
];
if (array_intersect(array_keys($dirty), $columns)){
    // 用戶電話或地址已被更改
}

老天尊的死期

2015年1月9日星期五

PHP常見問題

laravel判斷model的特定欄位是否被更改

沒有留言:

張貼留言

著作人

2015年1月9日 星期五

PHP常見問題

laravel判斷model的特定欄位是否被更改

沒有留言:

張貼留言

2015年1月9日星期五