python 正则表达式 re库 入门

参考：https://www.icourse163.org/learn/BIT-1001870001?tid=1467473478#/learn/content?type=detail&id=1248909693&cid=1276198042

def compile(pattern, flags=0):
    "Compile a regular expression pattern, returning a Pattern object."

def search(pattern, string, flags=0):
    """Scan through string looking for a match to the pattern, returning
    a Match object, or None if no match was found."""

def match(pattern, string, flags=0):
    """Try to apply the pattern at the start of the string, returning
    a Match object, or None if no match was found."""

def findall(pattern, string, flags=0):
    """Return a list of all non-overlapping matches in the string."""

def split(pattern, string, maxsplit=0, flags=0):
    """Split the source string by the occurrences of the pattern,
    returning a list containing the resulting substrings. 
    If maxsplit is nonzero, at most maxsplit splits occur,
    and the remainder of the string is returned as the final element
    of the list."""

def finditer(pattern, string, flags=0):
    """Return an iterator over all non-overlapping matches in the
    string.  For each match, the iterator returns a Match object.

    Empty matches are included in the result."""

def sub(pattern, repl, string, count=0, flags=0):
    """Return the string obtained by replacing the leftmost
    non-overlapping occurrences of the pattern in string by the
    replacement repl.  repl can be either a string or a callable;
    if a string, backslash escapes in it are processed.  If it is
    a callable, it's passed the Match object and must return
    a replacement string to be used."""

RE库默认使用贪婪匹配算法