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PHP字符串word末字符大小写互换

作者：佚名      php网站开发编辑：admin      更新时间：2022-07-23
php字符串Word末字符大小写互换要求

给出一个字符串如 “A journey of, a thousand 'miles' must can't \"begin\" with a single step.” ，通过 PHP 程序处理变成 “a journeY oF, A thousanD 'mileS' musT can'T "begiN" witH A singlE steP.”

注意：1、每个单词最后的字符如果是大写就变成小写，如果是小写就变成大写。2、需要考虑类似 can't 这种形式的转换。3、标点符号（只考虑 , ' " . ;）不用变化。

参考算法
<?php    function convertLastChar($str) {        $markArr = array(", ", "' ", "\" ", ". ", "; ");        $ret = "";        for ($i = 0, $j = strlen($str); $i < $j; $i++) {            if ($i < $j - 2) {                $afterStr = $str{$i + 1} . $str{$i + 2};            } else if ($i < $j - 1) {                $afterStr = $str{$i + 1} . " ";            }            if (in_array($afterStr, $markArr)                 || $i == $j - 1                 || $str{$i + 1} == " ") {                $ret .= strtoupper($str{$i}) === $str{$i}                     ? strtolower($str{$i})                     : strtoupper($str{$i});            } else {                $ret .= $str{$i};            }        }        return $ret;    }?>
测试
<?php    //test    $str1 = "A journey of, a thousand 'miles' must can't \"begin\" with a single step.";    $str2 = "A journey of, a thousand 'miles' must can't \"begin\" with a single step. ";    $str3 = "A journey of, a thousand 'miles' must can't \"begin\" with a single step. a ";    $str4 = "A journey of, a thousand 'miles' must can't \"begin\" with a single step. a B";    $str5 = "A journey of, a thousand 'miles' must can't \"begin\" with a single step. a b'";    $str6 = "A journey of, a thousand 'miles' must can't \"begin\" with a single step. a B\"";    echo "source:<br/>" . $str1 . "<br/>result:<br/>" . convertLastChar($str1) . "<br/><br/>";    echo "source:<br/>" . $str2 . "<br/>result:<br/>" . convertLastChar($str2) . "<br/><br/>";    echo "source:<br/>" . $str3 . "<br/>result:<br/>" . convertLastChar($str3) . "<br/><br/>";    echo "source:<br/>" . $str4 . "<br/>result:<br/>" . convertLastChar($str4) . "<br/><br/>";    echo "source:<br/>" . $str5 . "<br/>result:<br/>" . convertLastChar($str5) . "<br/><br/>";    echo "source:<br/>" . $str6 . "<br/>result:<br/>" . convertLastChar($str6) . "<br/><br/>";?>

结果：

source:A journey of, a thousand 'miles' must can't "begin" with a single step.result:a journeY oF, A thousanD 'mileS' musT can'T "begiN" witH A singlE steP.source:A journey of, a thousand 'miles' must can't "begin" with a single step. result:a journeY oF, A thousanD 'mileS' musT can'T "begiN" witH A singlE steP. source:A journey of, a thousand 'miles' must can't "begin" with a single step. a result:a journeY oF, A thousanD 'mileS' musT can'T "begiN" witH A singlE steP. A source:A journey of, a thousand 'miles' must can't "begin" with a single step. a Bresult:a journeY oF, A thousanD 'mileS' musT can'T "begiN" witH A singlE steP. A bsource:A journey of, a thousand 'miles' must can't "begin" with a single step. a b'result:a journeY oF, A thousanD 'mileS' musT can'T "begiN" witH A singlE steP. A B'source:A journey of, a thousand 'miles' must can't "begin" with a single step. a B"result:a journeY oF, A thousanD 'mileS' musT can'T "begiN" witH A singlE steP. A b"

我们可以看到，是符合预期的。

题目来源

http://blog.sijiaomao.com/?p=98，有改动（增加了can't这种），按改后的规则，原文答案全是错的。