首页 / 网页编程 / PHP / PHP字符串word末字符实现大小写互换的方法

本文实例讲述了PHP字符串word末字符实现大小写互换的方法。分享给大家供大家参考。具体实现方法如下：
一、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.”
这里需要注意：
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。
二、参考算法如下：
复制代码 代码如下:<?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;
    }
?>
测试代码如下：
复制代码 代码如下:<?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/>";
?>
运行结果如下：
复制代码 代码如下: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 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"
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"
希望本文所述对大家的PHP程序设计有所帮助。