32、正则表达式与数据库基础入门

正则表达式与数据库基础入门

正则表达式的应用

正则表达式在文本处理中起着重要作用，下面通过几个示例来展示其具体应用。

示例1：判断二进制序列是否为回文

以下代码用于判断输入的五位二进制序列是否为回文：

import re
text = input("Input a binary sequence of five figures: \n")
pattern = "(0.{3}0)|(1.{3}1)"
valid = False
# The input is checked for validity
if len(text) == 5:
    valid = True
    for i in text:
        if i != '0' and i != '1':
            valid = False
            break
# If the input is valid it is checked if it is capicua
if valid:
    x = re.search(pattern, text)
    if (x != None):
        print("Is capicua!")
    else:
        print("It is not capicua!")
# If the input is not valid and an error message appears:
else:
    print("ERROR: text is not valid")

此代码的执行流程如下：