PHP开发笔记系列（二）-字符串使用
   
    经过了《PHP开发笔记系列（一）-PDO使用》，今天开了关于PHP开发中字符串的处理，《PHP开发笔记系列（二）-字符串使用》，形成《PHP开发笔记系列》的第二篇。

    字符串是任何开发语言都必须处理的，在PHP中字符串可以使用单引号（'）或双引号（"）进行定义。那单引号和双引号不同之处在哪？那就是双引号中的变量会被变量值替换，而单引号中的内容将原样输出。下面将日常程序开发中会碰到的字符串处理场景整理。

1. 以数组形式访问字符串（strlen）

file:str-lengh.phpurl:http://localhost:88/str/str-lengh.php";        // for循环访问数组    //for($i=0; $i";    //}        // while循环访问数组    $i=0;    while($i";         $i++    }?>

file:str-strip-tags.phpurl:http://localhost:88/str/str-strip-tags.phphello world!
hello world!
hello world!
";        // 输出原始的字符串内容    echo "Original Text:";    echo $text."
";        // 去除所有html标签后进行输出    echo "Destination Text(After strip_tags)"."
";    echo strip_tags($text)."
";    // 字符串中的html标签不闭合    $text = "
hello world!";        // 去除所有html标签后进行输出    echo "Original Text:";    echo $text."
";        // 去除所有html标签后进行输出    echo "Destination Text(After strip_tags)"."
";    echo strip_tags($text)."
";?>

file:str-entities.phpurl:http://localhost:88/str/str-entities.php";        echo rawurlencode($text)."
";?>

file:str-wordwrap.phpurl:http://localhost:88/str/str-wordwrap.php";    echo $text."
";        echo $text."
";        echo "Destination text(after wrap):"."
";    echo wordwrap($text, 50, "
")."
";?>

file:str-strpos.phpurl:http://localhost:88/str/str-strpos.php

file:str-strreplace.phpurl:http://localhost:88/str/str-strreplace.php";    echo $text."
";        echo "
";        echo "Destination text(replace):"."
";    echo str_replace(" ", "__", $text)."
";    ?>

file:str-compare.phpurl:http://localhost:88/file/str-compare.php

file:str-sub.phpurl:http://localhost:88/file/str-sub.php';    echo 'Destination String: '.$newStr.'
';?>

file:str-count.phpurl:http://localhost:88/file/str-count.php

file:str-explode-implode.phpurl:http://localhost:88/str/str-explode-implode.php";    echo $text."
";        echo "
";        $sentenses = explode(". ", $text);    echo "Destination text(explode):"."
";    foreach ($sentenses as $sentense){        echo $sentense."
";    }        echo "
";        $newText= implode($sentenses, ". ");        echo "Destination text(implode):"."
";    echo $newText."
";    ?>

file:str-trim.phpurl:http://localhost:88/str/str-trim.php";    echo strlen($text)."
";        echo "
";        echo "Destination text(trim):"."
";    echo strlen(trim($text))."
"; ?>

file:str-printf.phpurl:http://localhost:88/str/str-printf.php