PHP字符串word末字符大小写互换

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: " . $str1 . " result: " . convertLastChar($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) . " ";?>

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。