php中的各種坑 · php

[TOC] # 字符串 == 比較類型強轉隱患 ~~~ // php 5 var_dump(md5('240610708') == md5('QNKCDZO'));//bool(true) var_dump(md5('aabg7XSs') == md5('aabC9RqS'));//bool(true) var_dump(sha1('aaroZmOk') == sha1('aaK1STfY'));//bool(true) var_dump(sha1('aaO8zKZF') == sha1('aa3OFF9m'));//bool(true) var_dump('0010e2' == '1e3');//10×10^2 = 1×10^3 bool(true) var_dump('0x1234Ab' == '1193131');//bool(true) var_dump('0xABCdef' == ' 0xABCdef');//bool(true) var_dump("603E-4234" == "272E-3063");//bool(true) var_dump('0e1' == '0e2'); //bool(true) // php 7 含十六進制字符串不再被認為是數字 http://php.net/manual/zh/migration70.incompatible.php var_dump('0x1234Ab' == '1193131');//bool(false) var_dump('0xABCdef' == ' 0xABCdef');//bool(false) var_dump("0x123" == "291");//bool(false) var_dump(is_numeric("0x123"));//bool(false) >>> md5('240610708') => "0e462097431906509019562988736854" >>> md5('QNKCDZO') => "0e830400451993494058024219903391" // php 是弱語言，會自動判斷數據類型,0eXXXXXXXXXX 轉成 0 了 //來自文檔：如果比較一個數字和字符串或者比較涉及到數字內容的字符串，則字符串會被轉換為數值并且比較按照數值來進行。此規則也適用于 switch 語句。當用 === 或 !== 進行比較時則不進行類型轉換，因為此時類型和數值都要比對。 >>> md5('QNKCDZO')==0 => true >>> md5('240610708')==0 => true // 使用 === 判斷官方都建議直接用password_hash加密 var_dump(md5('240610708') === md5('QNKCDZO'));//bool(false) //http://bayescafe.com/php/yuebaomei-ctf.html var_dump("42"=="0x2A");//bool(true) var_dump("1" == "01"); // 1 == 1 -> true var_dump("10" == "1e1"); // 10 == 10 -> true var_dump(100 == "1e2"); // 100 == 100 -> true var_dump("\x34\x32\x2E"=="42");//bool(true) var_dump("\001abc");//abc var_dump('\001abc');//\001abc $a = "1234567"; var_dump($a['test']);//1 var_dump(in_array(false, array('xxx')));//false empty('0');//false "133" == "0133"; 133 == "0133"; 133 == 0133; //因為0133是一個八進制數，轉成十進制是91 "0133" != 91; //字符串中的數字始終是十進制的，這個也可以理解 "0x10" == 16; //但是!，在十六進制中上面的說法又不成立了 "1e3" == 1000; //科學計數表示也一樣 #'string' == true，而且'string' == 0，但是，true != 0 null == 0; null < -1; $flag = "THIS IS FLAG"; if ("POST" == $_SERVER['REQUEST_METHOD']) { $password = $_POST['password'];//420.00000e-1 if (0 >= preg_match('/^[[:graph:]]{12,}$/', $password)) { echo 'Wrong Format'; exit; } while (TRUE) { $reg = '/([[:punct:]]+|[[:digit:]]+|[[:upper:]]+|[[:lower:]]+)/'; if (6 > preg_match_all($reg, $password, $arr)) break; $c = 0; $ps = array('punct', 'digit', 'upper', 'lower'); foreach ($ps as $pt) { if (preg_match("/[[:$pt:]]+/", $password)) $c += 1; } if ($c < 3) break; if ("42" == $password) echo $flag; else echo 'Wrong password'; exit; } } //https://segmentfault.com/q/1010000012046306 $red_money = 143.66; $receive_money = 14.55; $residue_money = $red_money > $receive_money ? $red_money - $receive_money : 0; $receive_money = $residue_money * 100; var_dump($receive_money);//12911 var_dump((int)$receive_money);/12910 var_dump(intval(12910.9));//int(12910) var_dump($receive_money*10000);//12910000 var_dump((int)($receive_money*10000));//12910999 var_dump(decbin($receive_money)); var_dump(decbin(12911)); ~~~ # PDO bindParam 要求第二個參數是一個引用變量 ~~~ $dbh = new PDO('mysql:host=localhost;dbname=test', "test"); $query = <<<QUERY INSERT INTO `user` (`username`, `password`) VALUES (:username, :password); QUERY; $statement = $dbh->prepare($query); $bind_params = array(':username' => "laruence", ':password' => "weibo"); foreach( $bind_params as $key => $value ){ $statement->bindParam($key, $value); } $statement->execute(); //期望執行 sql INSERT INTO `user` (`username`, `password`) VALUES ("laruence", "weibo"); // 實際執行 sql INSERT INTO `user` (`username`, `password`) VALUES ("weibo", "weibo"); //第一次循環 $value = $bind_params[":username"]; $statement->bindParam(":username", &$value); //此時, :username是對$value變量的引用 //第二次循環 $value = $bind_params[":password"]; //oops! $value被覆蓋成了:password的值 $statement->bindParam(":password", &$value); // 解決 foreach( $bind_params as $key => &$value ) { //注意這里 $statement->bindParam($key, $value); } return $statement->execute($params); ~~~ # php引用 ~~~ $arr = range(1,3); foreach($arr as &$v){ } foreach($arr as $v){ } print_r($arr);//[1,2,2] // 解決一 $arr = range(1,3); foreach($arr as &$v){ } unset($v); foreach($arr as $v){ } print_r($arr);//[1,2,3] // 解決二 $arr = range(1,3); foreach($arr as &$v){ } foreach($arr as $v2){ } print_r($arr);//[1,2,3] // 解決三 $arr = range(1,3); foreach($arr as &$v){ } foreach($arr as &$v){ } print_r($arr);//[1,2,3] ~~~ # array_merge vs + ~~~ $arr1 = array(1 => "one", "2" => "two", 3 => "three"); $arr2 = array(2 => "new two", 3 => "new three"); print_r($arr1 + $arr2); Array ( [1] => one [2] => two [3] => three ) print_r(array_merge($arr1, $arr2)); Array ( [0] => one [1] => two [2] => three [3] => new two [4] => new three ) ~~~ # 浮點數精度問題 ~~~ var_dump(15702>=(157.02*100));//bool(false) var_dump(11111>=(111.11*100));//bool(true) var_dump(bcsub(15702,(157.02*100)) >= 0);//bool(true) if(abs(15702-(157.02*100)) < 0.001) { echo "相等"; } else { echo "不相等"; } $f = 0.58; var_dump(intval($f * 100)); //57 0.58 * 100 = 57.999999999... ~~~ # in_array switch/case 松散比較 ~~~ $arr = ['a', 'pro' => 'php', 8, true]; var_dump(in_array(2, $arr)); // bool(true) var_dump(in_array('b', $arr)); // bool(true) var_dump(in_array(0, $arr)); // tbool(true) var_dump(in_array(null, $arr)); // bool(false) var_dump(in_array(2, $arr, true)); // bool(false) var_dump(in_array(0, $arr, true)); // bool(false) $name = 0; switch ($name) { case "a": //... break; case "b": //... break; } switch (strval($name)) { case "a": //... break; case "b": //... break; } //http://php.net/manual/zh/types.comparisons.php#types.comparisions-loose function test($var) { switch (true) { case 'apple' === $var: echo 'apple', PHP_EOL; break; case 0 === $var: echo '0', PHP_EOL; break; default: echo 'default', PHP_EOL; } } $arr = array('0', 0, 'apple'); foreach ($arr as $value) { test($value); } ~~~ # strpos ~~~ function getReferer($link) { $refMap = [ 'baidu' => '百度', 'sougou' => '搜狗', '360' => '360', 'google' => '谷歌' ]; foreach ($refMap as $key => $value) { if (strpos($link, $key) !== false) { return $value; } } return '其他'; } // https://secure.php.net/manual/zh/function.strpos.php 如果 needle 不是一個字符串，那么它將被轉換為整型并被視為字符的順序值。 echo getReferer('https://www.google.com/search?workd=google');//360 // 解決 function getReferer($link) { $refMap = [ 'baidu' => '百度', 'sougou' => '搜狗', '360' => '360', 'google' => '谷歌' ]; foreach ($refMap as $key => $value) { if (mb_strpos($link, $key) !== false) { //if (strpos($link, strval($key)) !== false) { return $value; } } return '其他'; } ~~~ # PHP 不同版本 curl 文件上傳 ~~~ //PHP的cURL支持通過給CURL_POSTFIELDS傳遞關聯數組（而不是字符串）來生成multipart/form-data的POST請求 https://blog.zsxsoft.com/post/5 if (class_exists('\CURLFile')) { $field = array('fieldname' => new \CURLFile(realpath($filepath))); } else { $field = array('fieldname' => '@' . realpath($filepath)); } ~~~ # foreach 順序 ~~~ $arr=[]; $arr[2] = 2; $arr[1] = 1; $arr[0] = 0; foreach ($arr as $key => $val) { echo $val;// 2 1 0 } while (list($key, $v) = each($arr)) { //獲取不到 foreach會自動reset，each之前, 先reset數組的內部指針 } for($i=0,$l=count($arr); $i<$l; $i++) { echo $arr[$i];// 0 1 2 } ~~~ # json_decode ~~~ >>> json_decode('php') => null // 對非 json 字符串并非返回 null >>> json_decode('0x123') => 291 echo json_encode(["name" => "php", "age" => "22"]) . "\n";// {"name":"php","age":"22"} echo json_encode([]) . "\n";//[] 返回這個會讓 APP 崩潰 echo json_encode((object)[]) . "\n";//{} >>> $a = 0.1 + 0.7 => 0.8 >>> printf('%.20f', $a) => 0.79999999999999993339 >>> json_encode($a) => "0.7999999999999999" >>> \YaJson::encode($a)//https://github.com/seekerliu/laravel-another-json => "0.8" ini_set('serialize_precision', 14); $a = 0.1 + 0.7; echo json_encode($a);//0.8 echo json_decode(0.7999999999999999);//0.8 ~~~ # strtotime('-x month') ~~~ date_default_timezone_set('Asia/Shanghai'); $t = strtotime('2017-08-31'); echo date('Ym',strtotime('- 1 month',$t));//201707 echo date('Ym',strtotime('- 2 month',$t));//201707 ? // $first_day_of_month = date('Y-m',strtotime('2017-08-31')) . '-01 00:00:01'; $t = strtotime($first_day_of_month); echo date('Ym',strtotime('- 1 month',$t));//201707 echo date('Ym',strtotime('- 2 month',$t));//201706 echo date("Ym", strtotime("-2 month", strtotime("first day of 2017-08-31")));//201706 ~~~ # BOM ~~~ //json 解析成 null 寫代碼時指定 utf-8 without bom function remove_utf8_bom($text) { $bom = pack('H*','EFBBBF'); $text = preg_replace("/^$bom/", '', $text); return $text; } // ps:PHP導出Excel 可能會亂碼，需要寫入 BOM頭 $content = pack('H*','EFBBBF'); fwrite($fp, $content); ~~~ # PHP解析大整數 ~~~ $shopId = 17978812896666957068; var_dump($shopId);//float(1.7978812896667E+19) $shopId= number_format(17978812896666957068); var_dump($shopId);//17978812896666957824 $shopId= strval(17978812896666957068); var_dump($shopId); $shopId = 17978812896666957068 . ''; var_dump($shopId);//float(1.7978812896667E+19) $shopId = '17978812896666957068'; var_dump($shopId); // 輸出 // string(20) "17978812896666957068" 超過PHP最大表示范圍的純整數，在MySQL中可以使用bigint/varchar保存，MySQL在查詢出來的時候會將其使用string類型保存的。對于賦值，在PHP里，如果遇到有大整數需要賦值的話，不要嘗試用整型類型去賦值$var = '17978812896666957068'; # ~~~ # curl獲取網頁內容出現亂碼 ~~~ curl_setopt($ch,CURLOPT_ENCODING,'gzip')//）如果抓取的網頁進行了gzip壓縮加入gzip解析 $data = file_get_contents("compress.zlib://".$url); //???? Header 里 Accept-Encoding:gzip 是告訴對方服務器使用 Gzip 進行傳輸。 ???? ~~~ # trim 中文亂碼 ~~~ echo rawurlencode('河北省');//%E6%B2%B3%E5%8C%97%E7%9C%81 echo rawurlencode('廣東省');//%E5%B9%BF%E4%B8%9C%E7%9C%81 echo rtrim('河北省', '省');//河北 echo rtrim('廣東省', '省');//廣?? //省的十六制作表示是e7 9c 81，而東的十六進制表示是e4 b8 9c，都出現了9c，哦~正因為是rtrim，所以rtrim('廣東省', '省')的時候把“東”的十六進制表示的最后一位也被trim掉了。同理rtrim('河北省', '省')不存在此問題 echo trim_cn('廣東省','省');//廣東 function trim_cn($str, $trim, $charset = 'UTF-8') { $len = mb_strlen($str, $charset); if (!$len) return; $t1 = $t2 = false;$o=$l=0; for($i=0;$i<$len;$i++) { $str1 = mb_substr($str, $i, 1, $charset); $str2 = mb_substr($str, $len-$i-1, 1, $charset); if($str1 == $trim && !$t1) $o++; else $t1 = true; if($str2 == $trim && !$t2) $l++; else $t2 = true; } return mb_substr($str, $o, ($len-$l-$o), $charset);; } ~~~ # __callStatic ~~~ //在對象中調用一個不可訪問方法時，__call() 會被調用 //在靜態上下文中調用一個不可訪問方法時，__callStatic() 會被調用目標方法非 public 時__callStatic 才會起作用。 class A{ public static function __callStatic($name, $arguments) { echo $name.'靜態方法不存在!'; } public function test() { echo 'test 方法'; } } A::test();//test 方法 ~~~ # mb_substr字符編碼 ~~~ $str = '北京市朝陽區'; var_dump(mb_substr($str,0,3));//預期輸出是：string(9) "北京市"，但是輸出確是：string(3) "北" //mb_substr這個函數在操作的時候如果沒有傳字符編碼，則按照默認的內部編碼操作字符串。PHP5.6之前的默認編碼都是ISO-8859-1，5.6之后的才是UTF8，UTF8模式下，一個中文字符占3個字節，而ISO-8859-1則是按照一個字節進行處理，所以自然取出來的是異常的字符串。 var_dump(mb_substr($str,0,3,'UTF-8'));//string(9) "北京市" ~~~ # url參數中的+替換為空格 ~~~ $name=str_replace('%20','+',$_GET['name']); //安全 base64 function urlsafeB64Decode($input) { $remainder = strlen($input) % 4; if ($remainder) { $padlen = 4 - $remainder; $input .= str_repeat('=', $padlen); } return base64_decode(strtr($input, '-_', '+/')); } function urlsafeB64Encode($input) { return str_replace('=', '', strtr(base64_encode($input), '+/', '-_')); } ~~~ # array Undefined offset ~~~ # php -a php > $a=[]; php > echo $a[1]; PHP Notice: Undefined offset: 1 in php shell code on line 1 php > $a=null; php > echo $a[1]; php > $a=4; php > echo $a[1]; ~~~ # 數組比較 ~~~ array("foo", "bar") != array("bar", "foo"); //這個時候，array就是數組 array("foo" => 1, "bar" => 2) == array("bar" => 2, "foo" => 1); //這個時候，array又變成了無序hash表 $first = array("foo" => 123, "bar" => 456); $second = array("foo" => 456, "bar" => 123); var_dump(array_diff($first, $second)); ==> array() ~~~ # 數組序列化 ~~~ $arrA = array('a', 'b', 'c'); echo json_encode($arrA) . "\n"; $arrB = array('a' => 1, 'b' => 2, 'c' => 3); echo json_encode($arrB) . "\n"; ["a","b","c"] {"a":1,"b":2,"c":3} $arrA = array(1 => 'a', 2 => 'b', 3 => 'c'); echo json_encode($arrA) . "\n"; $arrA = array(0 => 'a', 2 => 'b', 3 => 'c'); echo json_encode($arrA) . "\n"; {"1":"a","2":"b","3":"c"} {"0":"a","2":"b","3":"c"} //僅當數組的key是從0開始的整數，并且key連續不間斷，對其序列化的結果才是JS中的數組，也就是通常認為的PHP索引數組。 ~~~