PHP字符串如何实现word末字符实现大小写互换

PHP字符串如何实现word末字符实现大小写互换?希望下面的内容对你有所帮助，更多详情请关注应届毕业生考试网。

　　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:<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：

　　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"