PHP入門

php的四種不同的風格

<?php 程式碼 ?>
官方推薦風格
<? 程式碼 ?>
短標記風格，需配置檔案php.ini中開啟short+open_tag
<% 程式碼 %>
ASP風格，需配置檔案php.ini中開啟asp_tags
<script language=”php”> 程式碼 </script>
JavaScript標記的風格，這種風格在任何情況下都可以使用。

字串

單引號

變數和轉義序列都不會進行轉義

雙引號

PHP會處理雙引號括起來的字串、變數以及轉義序列。

<?php
//demo
	$a = "雙引號";
	echo "{$a}引起來的字串進行轉義\n";
	$b = '單引號';
	echo '$b引起來的字串不進行轉義\n';
	echo "\n";
	echo "$a,Hello";
?>
 

這裡要注意字串裡面如果需要使用變數的話需要用{}將變數括起來，或者在變數後面加一些符號，與後面的字元隔開。

字串切片

<?php
//demo
	$s = 'PHP is the best language in the world!';
	echo substr($s,0)."\n";
	echo substr($s,0,6)."\n";
	echo substr($s,-6,6)."\n";
	echo substr($s,2,-6)."\n;";
?>

字串查詢

<?php
//demo
	$s = 'PHP is the best language in the world! Php in my favorite! I just say PHP.';
	echo "字串長度為：" . strlen($s) . "\n";
	echo "PHP出現了" . substr_count($s,"PHP") . "次\n";
	echo strstr($s,"Php") . "\n";
	echo stristr($s, "Php") . "\n:";   //匹配時不區分大小寫
	echo stripos($s , "PHP") . "\n";    //返回第一次匹配中的位置
?>
 

字串替換

<?php
//demo
	$s = 'PHP is the best language in the world!';
	echo substr_replace($s, 'python', 0,3);
	
?>

正則

參考文件

陣列

組成

陣列由鍵值對組成，鍵可以是數字，也可以是字元。

<?php
//demo
	$arr = array(2 => "a" , 3 => "c" , "this" => 'that');
	echo '陣列元素個數：' .count($arr)."\n原陣列:";      //陣列鍵值對個數
	print_r($arr);        //列印陣列
	echo "\nksort:";
	ksort($arr);
	print_r($arr);        //ksort按鍵從小到大排序
	echo "\nasort:";
	asort($arr);         //asort按數值從小到大排序
	print_r($arr);
	echo "\nsort:";
	sort($arr);          //sort按數值從小到大排序
	print_r($arr);
	echo "\nrsort:";
	rsort($arr);         //rsort按索引從小到大排序
	print_r($arr);
	echo "\n";
?>
 

陣列操作符

• 使用+操作符號時，如果兩個陣列有相同的鍵，將不會新增。

<?php
//demo
	$arr1 = array('1' => 1, '2' => 2, '3' => 3, '4' => 4 );
	$arr2 = array('45' => 123, '6' => 8 );
	$arr3 = array('1' => 4, '6' => 2);
	var_dump($arr1 + $arr2);
	echo "\n";
	var_dump($arr1 + $arr3)
?>

訪問陣列

<?php
//demo
	$r = range('a','z');
	foreach ($r as $value) {
		echo "$value";
	}
	echo "\n=====================\n";
	foreach ($r as $key => $value) {
		echo "$key=>$value ";
	}
	echo "\n$r[5]";
?>

陣列的建立與新增

<?php
//demo
	$r = array('PHP' , "python" , "C" , "Java" , "C++" );
	print_r($r);echo "\n";
	$r[] = "Perl";
	print_r($r);echo "\n";
	$r[8] = "Ruby";
	print_r($r);echo "\n";
	$t = array('a' => "PHP" , "b" => "Python" , "c" => "C++" , "d" => "C++");
	print_r($t);
?>

陣列元素的新增與刪除

<?php
$r = array("PHP","Python","C","Java","C++");
print_r($r);echo "\n";
array_unshift($r,"Ruby","Perl");    //在陣列頭部新增
print_r($r);echo "\n";
array_push($r,"Go");                //在陣列尾部新增
print_r($r);echo "\n";
array_shift($r);                    //刪除陣列第一個元素
print_r($r);echo "\n";
array_pop($r);                      //刪除陣列第一個元素
print_r($r);echo "\n";
?>

陣列與字串互轉

<?php
$r = array('PHP',"Python","Perl");
echo "初始化";print_r($r);echo "\n";
$r = implode('==',$r);
echo "After implode:  ";print_r($r);echo "\n";
$r = explode("==",$r);
echo "After explode:  ";print_r($r);echo "\n";
?>

in_array()判斷鍵是否在陣列中

<?php
$r = array("a" => 'PHP',"b" => "Python","c" => "Perl");
if (in_array('PHP', $r)) echo "PHP in array(r)";
else echo "PHP not in array(r)";
?>

array_merge()合併陣列

<?php
$r = array("a" => 'PHP',"b" => "Python","c" => "Perl");
$t = array("d" => "C" , "a" => "Go");         //這裡的a會將原來的a覆蓋掉
$n = array_merge($r,$t);
print_r($n);
?>

array_combine()

<?php
$r = array("a" => 'PHP',"b" => "Python","c" => "Perl");
$t = array("1" => "a" , "2" => "b" , '3' => 'c');
$n = array_combine($r,$t);
print_r($n);
?>

extrace()將陣列轉換成標量變數

<?php
$r = array("a" => 'PHP',"b" => "Python","c" => "Perl");
extract($r);
echo $a;echo "\n";
echo $b;echo "\n";
echo $c;echo "\n";
?>

array_keys()和array_values()

<?php
$r = array("a" => 'PHP',"b" => "Python","c" => "Perl");
print_r(arrat_keys($r));
echo "\n";
print_r(array_values($r));
echo "\n";
?>