Python正则表达式（re.search() VS re.findall()） _Pythonseach和findall

先决条件：带示例的正则表达式|Python
一种正则表达式(有时称为Rational表达式)是定义搜索模式的一系列字符, 主要用于与字符串进行模式匹配或字符串匹配(即类似” 查找和替换” 的操作)。正则表达式是一种将模式与字符序列匹配的通用方法。
模组正则表达式(RE)指定与其匹配的一组字符串(模式)。要了解RE类比, 元字符有用, 重要且将在模块功能中使用re.
一共有14个元字符, 将在功能中进行讨论：

\Used to drop the special meaning of character following it (discussed below) []Represent a character class ^Matches the beginning $Matches the end .Matches any character except newline ?Matches zero or one occurrence. |Means OR (Matches with any of the characters separated by it. *Any number of occurrences (including 0 occurrences) +One ore more occurrences {}Indicate number of occurrences of a preceding RE to match. ()Enclose a group of REs

search()search()方法要么返回None(如果模式不匹配), 要么返回re.MatchObject包含有关字符串匹配部分的信息。此方法在第一个匹配项后停止, 因此它最适合于测试正则表达式, 而不是提取数据。
例子：

# A Python program to demonstrate working of re.match(). import re # Lets use a regular expression to match a date string # in the form of Month name followed by day number regex = r "([a-zA-Z]+) (\d+)"match = re.search(regex, "I was born on June 24" ) if match ! = None : # We reach here when the expression "([a-zA-Z]+) (\d+)" # matches the date string. # This will print [14, 21), since it matches at index 14 # and ends at 21. print ( "Match at index % s, % s" % (match.start(), match.end()))# We us group() method to get all the matches and # captured groups. The groups contain the matched values. # In particular: # match.group(0) always returns the fully matched string # match.group(1) match.group(2), ... return the capture # groups in order from left to right in the input string # match.group() is equivalent to match.group(0) # So this will print "June 24" print ( "Full match: % s" % (match.group( 0 )))# So this will print "June" print ( "Month: % s" % (match.group( 1 )))# So this will print "24" print ( "Day: % s" % (match.group( 2 )))else : print ( "The regex pattern does not match." )

输出如下：

Match at index 14, 21 Full match: June 24 Month: June Day: 24

re.findall()以字符串列表形式返回字符串中所有不重复的模式匹配项。从左到右扫描字符串, 并以找到的顺序返回匹配项。
例子：

# A Python program to demonstrate working of # findall() import re # A sample text string where regular expression # is searched. string = """Hello my Number is 123456789 and my friend's number is 987654321"""# A sample regular expression to find digits. regex = '\d+'match = re.findall(regex, string) print (match)

输出如下：