In PHP, determine whether a string contains a specific word, the strpos() function is preferred to check whether the keyword exists. This method is efficient but case-sensitive; if it is necessary to be case-insensitive, the strpos() function can be used; to ensure that the complete word is precisely matched, a regular expression should be used to process special characters with \b word boundaries and preg_quote(); for multi-word judgment or complex scenarios, strpos() can be called continuously, logical conditions, or traverse keyword arrays can be traversed to match.
It is not difficult to determine whether a string contains a specific word in PHP. The key is to choose the right method, which can match accurately without accidentally hurting other similar content.
Use strpos() to determine whether there are keywords
This is one of the most common and more efficient methods. strpos() function can find where a string first appears in another string. If it cannot be found, false will be returned.
if (strpos($text, $word) !== false) {
// Include this word} It should be noted that this method is case sensitive . If you want to be case-insensitive, you can use stripos() instead. In addition, it will match all occurrences, including partial matches (such as searching for "cat" will be misjudged in "category").
Exactly match the entire word: use regular expressions
If you want to make sure that you only match the complete words and not appear as part of other words, it is recommended to use regular expressions:
if (preg_match('/\b' . preg_quote($word, '/') . '\b/i', $text)) {
// The full word was found}Here are a few key points:
-
\brepresents the word boundary, ensuring that the matching is a complete word. -
preg_quote()is to prevent regular errors from occurring in$word. - The
/iflag indicates that upper and lower case is ignored.
For example, when searching for "apple", it matches "I like apple", but it won't match "I like pineapple".
What to do if you judge multiple words or more complex scenarios?
Sometimes you may not just look up one word, but multiple words, or do some logical combinations. At this time you can consider the following methods:
- Multiple words must contain : use
strpos()in succession or nest multiple regular expressions. - Choose any of them : use
||to connect multiple judgments. - Blacklist/whitelist filtering : You can put keywords in an array and then make a loop to judge.
For example:
$keywords = ['apple', 'banana', 'orange'];
foreach ($keywords as $keyword) {
if (strpos($text, $keyword) !== false) {
// One of the words break was found;
}
}If it is more complex rules, such as supporting wildcards, fuzzy matching, etc., it may be necessary to introduce a more advanced text processing library.
Basically these common methods are. Use strpos simply and directly, and use regularity if it needs exact matching. Intermediate situations can be used in combination according to specific needs.
The above is the detailed content of PHP check if a string contains a specific word. For more information, please follow other related articles on the PHP Chinese website!
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