php知识点复习之字符串

这些可都是辛辛苦苦敲出来的记得多回头来看看啊一定！！！

/*echo <<< mark
qqqqqq\nqqqqqq<br>qqqqqqqqqqqqq\rqqqqqqqqqqqqqqqqqq
mark*/
//技术标志要另起一行，并且是顶格写！
//作用跟""类似
//最致命的一点是：mark后面不能有任何符号，就是它必须用在代码的最后部分






$a = "aaaaaaaaaa";
$b = "bbbbbbbbbb";
$c = print($a);


echo "<br>";
echo $c;
echo "<br>";
echo $a,$b;


//5b二进制格式；%c ASCII格式
$format = "%b,%c";
printf($format,100,200);
echo sprintf($format,100,200);
echo "<br>";




$str = "abcdefghijklmnopqrstyvwxyz";
$width = 4;
$break = "\t";
echo wordwrap($str,$width,$break,true);


/*strtoupper();
strtolower();
ucwords();*/


//strlen()
//字符串中的空格也算一个啊


//substr_count(string str,string sub,[int start,int length])的使用
$words = "ran zhang li ni ran ran";
$handle = "ran";
$count = substr_count($words,$handle);
echo $count;




//mixed str_word_count(string $str,[int format,string $child]);
//format 0：默认值，返回单词数目
// 1：返回单词的数组，键是索引值
// 2：返回单词的数组，键是单词首字母的位置




//查找子串
$a1 = "aaaaaabdddddd";
$a2 = "b";
$a3 = strstr($a1,$a2);
echo $a3;
//输出bdddddd




//位置查找，跟上面的几乎一样就是返回的是位置
//int strpos(string $a,string b,[int offset]);






//字符串复制
echo "<br>";
$input = "zhangran";
$number = 10;
$str = str_repeat($input,$number);
echo $str;




//字符串的反转
echo "<br>";
$a4 = strrev("abc");
echo $a4;




//替换
//substr_replace(mixed $string,string $replacement,int $start,[int $length])




//切分
echo "<br>";
$a5 = "hello,world,i,am,the,only,one";
$separator = ",";
$a7 = 3;
$array = explode($separator,$a5,$a7);
print_r($array);


echo "<br>";
$a8 = "qqqqqqqqqqqqqqqqqq";
$a9 = 4;
$b3 =str_split($a8,$a9);
print_r($b3);
//如果不能被整出的 先以前面的先



//合并
echo "<br>";
$b4 = array("aaa","bbb","ccc");
$b5 = ",";
echo implode($b5,$b4);


//字符串的比较
//int strcmp(str1,str2)这是完全比较


//strncmp(str1,str2,len)比较两个字符串的前len个字符串是否相等