php返回字符串所有信息的函数count_chars()
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实例
返回一个字符串,包含所有在 "Hello World!" 中使用过的不同字符(模式 3):
<?php $str = "Hello World!"; echo count_chars($str,3); ?>
定义和用法
count_chars() 函数返回字符串所用字符的信息(例如,ASCII 字符在字符串中出现的次数,或者某个字符是否已经在字符串中使用过)。
语法
count_chars(string,mode)
参数 描述
string 必需。规定要检查的字符串。
mode 可选。规定返回模式。默认是 0。有以下不同的返回模式:
0 - 数组,ASCII 值为键名,出现的次数为键值
1 - 数组,ASCII 值为键名,出现的次数为键值,只列出出现次数大于 0 的值
2 - 数组,ASCII 值为键名,出现的次数为键值,只列出出现次数等于 0 的值
3 - 字符串,带有所有使用过的不同的字符
4 - 字符串,带有所有未使用过的不同的字符
技术细节
返回值: 取决于指定的 mode 参数。
PHP 版本: 4+
更多实例
实例 1
返回一个字符串,包含所有在 "Hello World!" 中未使用过的字符(模式 4):
<?php $str = "Hello World!"; echo count_chars($str,4); ?>
实例 2
在本实例中,我们将使用 count_chars() 来检查字符串,返回模式设置为 1。模式 1 将返回一个数组,ASCII 值为键名,出现的次数为键值:
<?php $str = "Hello World!"; print_r(count_chars($str,1)); ?>
实例 3
统计 ASCII 字符在字符串中出现的次数另一个实例:
<?php $str = "PHP is pretty fun!!"; $strArray = count_chars($str,1); foreach ($strArray as $key=>$value) { echo "The character <b>'".chr($key)."'</b> was found $value time(s)<br>"; } ?>
count_chars实例
<?php $data = "Two Ts and one F." ; foreach ( count_chars ( $data , 1 ) as $i => $val ) { echo "There were $val instance(s) of \"" , chr ( $i ) , "\" in the string.<br/>" ; } ?>
运行结果:
There were 4 instance(s) of " " in the string. There were 1 instance(s) of "." in the string. There were 1 instance(s) of "F" in the string. There were 2 instance(s) of "T" in the string. There were 1 instance(s) of "a" in the string. There were 1 instance(s) of "d" in the string. There were 1 instance(s) of "e" in the string. There were 2 instance(s) of "n" in the string. There were 2 instance(s) of "o" in the string. There were 1 instance(s) of "s" in the string. There were 1 instance(s) of "w" in the string.
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