PHP Combat Common code example

1 outputs an array in turn. Each input is 3 lines in a row.

In a small detail, it is said that $i < sizeof ($len) each cycle to calculate the length of the array, whether it is wasteful of performance. -----Answer: 1 You observe very fine. 2 Now the interpreter is smarter, and this problem is automatically optimized for processing.

 for ($i  $i<sizeof($len$i+ +)     {if$i$i Echo "<br>";    Echo $arr [$i];}

2 string does not allow special characters to appear.

        $chinese= "\x{4e00}-\x{9fa5}"; // Chinese match        $pattern= "/^[a-za-z0-9 ($chinese)]+$/u"; // plus English, digital matching        if (! Preg_match ($pattern,$nick _name)) {                exit("Do not allow special characters");        }

3 Pay the strlen and substr functions of the utf-8. (Seek utf-8 string length, utf-8 substring)

   //Utf-8 seeking utf-8 string length   functionStrlen_utf8 ($str)   {        $i= 0; $count= 0; $len=strlen($str);  while($i<$len) {            $CHR=Ord($str[$i]); $count++; $i++; if($i>=$len)                 Break; if($CHR& 0x80) {                $CHR<<= 1;  while($CHR& 0x80) {                    $i++; $CHR<<= 1; }            }        }        return $count; }   //The UTF-8 substring is evaluated.        functionSubStringUtf8 ($str,$start,$lenth) {        $len=strlen($str); $r=Array(); $n= 0; $m= 0;  for($i= 0;$i<$len;$i++) {            $x=substr($str,$i, 1); $a=Base_convert(Ord($x), 10, 2); $a=substr(' 00000000 '.$a,-8); if($n<$start) {                if(substr($a, 0, 1) = = 0) {                } ElseIf(substr($a, 0, 3) = = 110) {                    $i+ = 1; } ElseIf(substr($a, 0, 4) = = 1110) {                    $i+ = 2; }                $n++; } Else {                if(substr($a, 0, 1) = = 0) {                    $r[] =substr($str,$i, 1); } ElseIf(substr($a, 0, 3) = = 110) {                    $r[] =substr($str,$i, 2); $i+ = 1; } ElseIf(substr($a, 0, 4) = = 1110) {                    $r[] =substr($str,$i, 3); $i+ = 2; } Else {                    $r[] = "; }                if(++$m>=$lenth) {                     Break; }            }        }        return Join("",$r); }    

4 decimal digit subtraction, easy to lose precision, using mathematical functions.

$sum=Bcadd($a,$b, 4);//A+b retains 4 decimal places. $diff=bcsub($a,$b, 4);//A -B retains 4 decimal places. $mul=Bcmul($a,$b, 4);//A*b retains 4 decimal places. $div=Bcdiv($a,$b, 4);//A/b reserved 4-bit decimal B cannot be 0.

5 using transactions. (Different framework code is not the same, here is the example of Yii)

$trans = Yii::app ()->db->begintransaction ();  // creates a transaction.  $trans->commit ();   // Transaction Commit $trans->rollback ();   // Transaction Rollback

6 exception handling. (In a production environment, you do not want to expose errors to the external, and when the program executes unexpectedly, the database rolls back processing.) ）

       Try {            $trans= Yii::app ()->db->BeginTransaction (); //... Intermediate code of Execution            $trans->commit ();//Transaction Commit}Catch(Exception $e) {            Log($e->getmessage ());//Log record exception information            $trans->rollback ();//Transaction Rollback}

PHP Combat Common code example