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：

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：

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:
" . $str1 . "
result:
" . convertLastChar($str1) . "

"; echo "source:
" . $str2 . "
result:
" . convertLastChar($str2) . "

"; echo "source:
" . $str3 . "
result:
" . convertLastChar($str3) . "

"; echo "source:
" . $str4 . "
result:
" . convertLastChar($str4) . "

"; echo "source:
" . $str5 . "
result:
" . convertLastChar($str5) . "

"; echo "source:
" . $str6 . "
result:
" . convertLastChar($str6) . "

"; ?>

运行结果如下：

代码如下:

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. 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。