How Can I Make PHP\'s `preg_match()` Case-Insensitive?

Ignoring Case in preg_match()

When performing pattern matching using PHP's preg_match() function, you may encounter situations where case sensitivity becomes a factor. To make preg_match() case insensitive, you can employ the following technique:

Solution:

The key to case insensitivity in preg_match() lies in adding the i modifier after the delimiter. For instance, consider the following case:

preg_match("#(.{100}$keywords.{100})#", strip_tags($description), $matches);

In this example, the goal is to display 100 characters on each side of the search string $keywords. While this code is functional, it's case sensitive. To make it case insensitive, add the i modifier as follows:

preg_match("#(.{100}$keywords.{100})#i", strip_tags($description), $matches);

Alternatively, if your delimiter is a forward slash "/", you can add the i modifier after it, as seen in the following example:

preg_match("/your_regexp_here/i", $s, $matches); // i means case insensitive

Effect of the i Modifier:

By specifying the i modifier, you instruct preg_match() to ignore case differences in the matching process. This means that if the target string contains either uppercase or lowercase letters matching the pattern, the match will still succeed.

Example:

Consider the pattern:

"/abc/"

With the i modifier applied, this pattern will match the strings "ABC", "abc", and "aBc". Without the i modifier, only the exact string "abc" would be matched.

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