1 $str='hello';
2 echo "str is $str";
3 echo "<br />";
4 echo 'str is $str';

1 $i='I';
2 $love=' Love';
3 $you=' You';
4 $hi=$i.$love.$you;    //连接字符串
5 echo $hi;

1 $str="   string    ";
2 $str1=trim($str);    //去除两边空格
3 $str=rtrim($str);    //去除右边空格
4 $str=ltrim($str3);    //去除左边空格

 1 //获取英文字符串长度
 2 $love="I love you";
 3 $len=strlen($love);
 4 echo $len;
 5 echo "<br />";
 6 //获取中文字符串的实际占用长度
 7 $love="我爱你！";
 8 $len=strlen($love);
 9 echo $len;
10 echo "<br />";
11 //获取中文汉字个数
12 $love="我爱你！";
13 $len=mb_strlen($love,"UTF8");
14 echo $len;

1 //英文字符串截取
2 $love="I love you";
3 echo substr($love, 2,4);
4 echo "<br />";
5 //中文字符串截取
6 $love="我爱你啊啊啊";
7 echo mb_substr($love, 0,3,'utf8');

1 $str = 'What is your name?';
2 echo strpos($str,'name');

1 $str = 'I Love China';
2 $replace=str_replace('China','you',$str);
3 echo $replace;

1 $str = '100.1';
2 $result=sprintf('%01.3f',$str);
3 echo $result;

1 //合并字符串
2 $arr = array('Hello', 'World!');
3 $result = implode('-', $arr);
4 print_r($result);
5 echo "<br />";
6 //分隔字符串
7 $str = 'sun-moon-star';
8 $result=explode('-',$str);
9 print_r($result);

1 $str = "what's this?";
2 echo addslashes($str);