PHP入门
php的四种不同的风格
<?php 代码 ?>
官方推荐风格
<? 代码 ?>
短标记风格，需配置文件php.ini中开启short+open_tag
<% 代码 %>
ASP风格，需配置文件php.ini中开启asp_tags
<script language=”php”> 代码 </script>
JavaScript标记的风格，这种风格在任何情况下都可以使用。
字符串
单引号
变量和转义序列都不会进行转义
双引号
PHP会处理双引号括起来的字符串、变量以及转义序列。
<?php
//demo
$a = "双引号";
echo "{$a}引起来的字符串进行转义
";
$b = '单引号';
echo '$b引起来的字符串不进行转义
';
echo "
";
echo "$a,Hello";
?>
这里要注意字符串里面如果需要使用变量的话需要用{}将变量括起来，或者在变量后面加一些符号，与后面的字符隔开。
字符串切片
<?php
//demo
$s = 'PHP is the best language in the world!';
echo substr($s,0)."
";
echo substr($s,0,6)."
";
echo substr($s,-6,6)."
";
echo substr($s,2,-6)."
;";
?>
字符串查找
<?php
//demo
$s = 'PHP is the best language in the world! Php in my favorite! I just say PHP.';
echo "字符串长度为：" . strlen($s) . "
";
echo "PHP出现了" . substr_count($s,"PHP") . "次
";
echo strstr($s,"Php") . "
";
echo stristr($s, "Php") . "
:"; //匹配时不区分大小写
echo stripos($s , "PHP") . "
"; //返回第一次匹配中的位置
?>
字符串替换
<?php
//demo
$s = 'PHP is the best language in the world!';
echo substr_replace($s, 'python', 0,3);
?>
正则
参考文档
数组
组成
数组由键值对组成，键可以是数字，也可以是字符。
<?php
//demo
$arr = array(2 => "a" , 3 => "c" , "this" => 'that');
echo '数组元素个数：' .count($arr)."
原数组:"; //数组键值对个数
print_r($arr); //打印数组
echo "
ksort:";
ksort($arr);
print_r($arr); //ksort按键从小到大排序
echo "
asort:";
asort($arr); //asort按数值从小到大排序
print_r($arr);
echo "
sort:";
sort($arr); //sort按数值从小到大排序
print_r($arr);
echo "
rsort:";
rsort($arr); //rsort按索引从小到大排序
print_r($arr);
echo "
";
?>
数组操作符
- 使用
+操作符号时，如果两个数组有相同的键，将不会添加。
<?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 + $arr2);
echo "
";
var_dump($arr1 + $arr3)
?>
访问数组
<?php
//demo
$r = range('a','z');
foreach ($r as $value) {
echo "$value";
}
echo "
=====================
";
foreach ($r as $key => $value) {
echo "$key=>$value ";
}
echo "
$r[5]";
?>
数组的创建与添加
<?php
//demo
$r = array('PHP' , "python" , "C" , "Java" , "C++" );
print_r($r);echo "
";
$r[] = "Perl";
print_r($r);echo "
";
$r[8] = "Ruby";
print_r($r);echo "
";
$t = array('a' => "PHP" , "b" => "Python" , "c" => "C++" , "d" => "C++");
print_r($t);
?>
数组元素的添加与删除
<?php
$r = array("PHP","Python","C","Java","C++");
print_r($r);echo "
";
array_unshift($r,"Ruby","Perl"); //在数组头部添加
print_r($r);echo "
";
array_push($r,"Go"); //在数组尾部添加
print_r($r);echo "
";
array_shift($r); //删除数组第一个元素
print_r($r);echo "
";
array_pop($r); //删除数组第一个元素
print_r($r);echo "
";
?>
数组与字符串互转
<?php
$r = array('PHP',"Python","Perl");
echo "初始化";print_r($r);echo "
";
$r = implode('==',$r);
echo "After implode: ";print_r($r);echo "
";
$r = explode("==",$r);
echo "After explode: ";print_r($r);echo "
";
?>
in_array()判断键是否在数组中
<?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()合并数组
<?php
$r = array("a" => 'PHP',"b" => "Python","c" => "Perl");
$t = array("d" => "C" , "a" => "Go"); //这里的a会将原来的a覆盖掉
$n = array_merge($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()将数组转换成标量变量
<?php
$r = array("a" => 'PHP',"b" => "Python","c" => "Perl");
extract($r);
echo $a;echo "
";
echo $b;echo "
";
echo $c;echo "
";
?>
array_keys()和array_values()
<?php
$r = array("a" => 'PHP',"b" => "Python","c" => "Perl");
print_r(arrat_keys($r));
echo "
";
print_r(array_values($r));
echo "
";
?>
