如何使用php查找字符串中以特定leter或元素结尾和开头的单词

我使用str_word_count（）计算一个单词在文本中出现的次数，但我真正想要的是只计算以

'[word here]'开头和结尾的特定单词。

$text = "Degree binb 'Information-Systems', 'Computer-Science' , or other KM-relevant field required; graduate degree preferred.";

$words = str_word_count($text, 1); 
$frequency = array_count_values($words);
arsort($frequency);
echo '<pre>';
print_r($frequency);
echo '</pre>';

使用

substr（）

检查字符串的开头/结尾是否等于要搜索的其他字符串：

正如您所注意到的，若要从字符串末尾进行比较，请使用负$start值

对于长度参数，请使用

strlen（）

获取字符串长度：

---

PHP伪代码示例：

$prefixed_words = find_words_prefix("Degree binb 'Information-Systems', 'Computer-Science' , or other KM-relevant field required; graduate degree preferred.", "D");

print_r($prefixed_words);

---

类似的函数可用于后置单词

要查找单引号中的所有单词，请使用带有

preg\u match\u all（）的正则表达式

：

这将输出：

function find_words_prefix($text, $prefix)
{
  $words = array_filter(explode(' ', $text), 'strlen'); // get only non-emoty words
  $prefixed_words = array();
  $prefix_len = strlen($prefix);
 foreach ($words as $word)
{
if (strlen($word) < $prefix_len) continue; // no use testing this word as it is smaller than prefix
if ( 0 === strpos($word, $prefix) ) $prefixed_words[] = $word;
}
return $prefixed_words;
}

$prefixed_words = find_words_prefix("Degree binb 'Information-Systems', 'Computer-Science' , or other KM-relevant field required; graduate degree preferred.", "D");

print_r($prefixed_words);

$text = "Degree binb 'Information-Systems', 'Computer-Science' , or other KM-relevant field required; graduate degree preferred.";

preg_match_all("/'([^']+)'/", $text, $matches);

var_dump($matches[1]);
echo "Found " . count($matches[1]) . " matches." . PHP_EOL;

array(2) {
  [0] =>
  string(19) "Information-Systems"
  [1] =>
  string(16) "Computer-Science"
}
Found 2 matches.