PHP生成树的方法
437
2023-12-08
(PHP 4, PHP 5)
strtr — 转换指定字符
说明
string strtr ( string$str
, string $from
, string $to
)
string strtr
( string $str
, array $replace_pairs
)
该函数返回 str 的一个副本，并将在 from 中指定的字符转换为 to 中相应的字符。
比如， $from[$n]中每次的出现都会被替换为
$to[$n]，其中 $n 是两个参数都有效的位移(offset)。
如果 from 与 to 长度不相等，那么多余的字符部分将被忽略。 str 的长度将会和返回的值一样。
If given two arguments, the second should be an array in the form array('from' => 'to', ...). The return value is a string where all the occurrences of the array keys have been replaced by the corresponding values. The longest keys will be tried first. Once a substring has been replaced, its new value will not be searched again.
In this case, the keys and the values may have any length, provided that
there is no empty key; additionally, the length of the return value may
differ from that of str.
However, this function will be the most efficient when all the keys have the
same size.
参数
str
待转换的字符串。
from
字符串中与将要被转换的目的字符 to 相对应的源字符。
to
字符串中与将要被转换的字符 from 相对应的目的字符。
replace_pairs
参数 replace_pairs 可以用来取代 to 和 from 参数，因为它是以 array('from' => 'to', ...) 格式出现的数组。
返回值
返回转换后的字符串。
如果 replace_pairs 中包含一个空字符串（""）键，那么将返回 FALSE。
If the str is not a scalar
then it is not typecasted into a string, instead a warning is raised and
NULL is returned.
范例
Example #1 strtr() 范例
<?php
$addr = strtr($addr, "äåö", "aao");
?>
The next example shows the behavior of strtr() when called with only two arguments. Note the preference of the replacements ("h" is not picked because there are longer matches) and how replaced text was not searched again.
Example #2 使用两个参数的 strtr() 范例
<?php
$trans = array("hello" => "hi", "hi" => "hello");
echo strtr("hi all, I said hello", $trans);
?>
以上例程会输出：
hello all, I said hi
The two modes of behavior are substantially different. With three arguments, strtr() will replace bytes; with two, it may replace longer substrings.
Example #3 strtr() behavior comparison
<?php
echo strtr("baab", "ab", "01"),"n";
$trans = array("ab" => "01");
echo strtr("baab", $trans);
?>
以上例程会输出：
1001 ba01
参见
str_replace() - 子字符串替换 preg_replace() - 执行一个正则表达式的搜索和替换
