本文實例講述了PHP字符串word末字符實現大小寫互換的方法。分享給大家供大家參考。具體實現方法如下：
一、要求：
給出一個字符串如 “A journey of, a thousand 'miles' must can't /"begin/" with a single step.” ，通過 PHP 程序處理變成 “a journeY oF, A thousanD 'mileS' musT can'T "begiN" witH A singlE steP.”
這里需要注意：
1、每個單詞最后的字符如果是大寫就變成小寫，如果是小寫就變成大寫。
2、需要考慮類似 can't 這種形式的轉換。
3、標點符號（只考慮 , ' " . ;）不用變化。
二、參考算法如下：
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;
}
?>
測試代碼如下：
//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/>";
?>
運行結果如下：
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"
希望本文所述對大家的PHP程序設計有所幫助。
