The preg_split() function is an inbuilt function in PHP which is used to convert the given string into an array. The function splits the string into smaller strings or sub-strings of length which is specified by the user. If the limit is specified then small string or sub-strings up to limit return through an array. The preg_split() function is similar to explode() function but the difference is used to the regular expression to specify the delimiter but explode is not used it.