CARET symbol (^):
matching beggining of stringDOLLAR symbol ($):
matching end of stringDOT symbol (.):
matching any characterSTAR symbol (*):
matching the preceding character 0 or more timesPLUS symbol (+):
matching the preceding character 1 or more timesQUESTION symbol (?):
matching the preceding character 0 or 1 timeDIGIT (\d):
matching digits 0-9ALPHA (\w):
matching alphabets a-zA-ZCHAR_CLASS ([...]):
matching any characters in the set
The engine provides a match function used as:
void match(char *pattern, char *text);
It furthur compiles the regex pattern into a form usable in the next stages.