关于Python的字符串

Python字符串

Python的字符串是一种不可变的字符序列。同时支持索引，分片，遍历等操作。

创建

通过单引号，双引号，三引号都可以创建字符串！

s01 = 'China'
s02 = "China"
s03 = """China"""
s04 = '''China'''
s01 == s02 == s03 == s04
True

常见的操作

转义

方法	含义
\t	横向制表符
\b	退格
\v	纵向制表符
\'	表示单引号
\"	表示双引号
\\	表示反斜杠
\n	换行

print("She\tcome\tfrom\tChina")
print("She\bcome\bfrom\bChina")
print("She\vcome\vfrom\vChina")
print("She\'come\'from\'China")
print("She\"come\"from\"China")
print("She\\come\\from\\China")
print("She\ncome\nfrom\nChina")

She come    from    China
ShcomfroChina
She�come�from�China
She'come'from'China
She"come"from"China
She\come\from\China
She
come
from
China

类型转换

通过str()可以将int类型转换成str类型

print(type(66666))
print(type(str(66666)))
<class 'int'>
<class 'str'>

拼接复制合并字符串

a="She ";b="come ";c="from ";d="china "
print(a+b+c+d)
print(a*4+b*3+c*2+d*1)
a = ["she come"];b =["from china"]
print(" ".join(a+b))

She come from china
She She She She come come come from from china
she come from china

拼接合并对比
import timeit
   ...: print(timeit.timeit("s ='';s += str(n for n in range(0,100000))",number=100000))
   ...: print(timeit.timeit("l =[];l.append(str(n for n in range(0, 100000)));s=''.join(l)",number=100000))
   ...:
0.12783753898111172
0.14433829998597503

提取字符串

通过偏移量可以提取想要的字符

info01="She come from China!"
print(info01[1])
print(info01[-1])

字符串的分片操作

字符串是支持分片操作的

pi="3.1415926535898"
print(pi[:])
print(pi[1:])
print(pi[:8])
print(pi[4:8])
print(pi[1:10:2])
3.1415926535898
.1415926535898
3.141592
1592
.4525

获取字符串的长度

通过内置函数len可以获取字符串的长度

len(pi)

分割字符串

#info02.split()
info02="She come from China and she lives in beijing ,She don't have any brothers or sisters"
info02.split("and")
info02.split(",")
path ='http://www.baidu.com/abcd/club'
namespace =path.split('//')[1].split('/')[0]
print(namespace)
url = path.split('//')[1].split('/')[1:]
print (url)

字符串的格式化

个人觉得format这种方式比%s那种更好一些

name = "zhangwen"
id = "007"
print("no data available for person with id:{}, name:{}.".format(id, name))

字符串的一些操作函数

info03="Lisa come from China, she don't have any brothers or sisters, she lives in singapore."
print(info03.startswith("China"))
print(info03.endswith("singapore"))
print(info03.find("she"))
print(info03.rfind("she"))
print(info03.count("she"))
print(info03.strip("."))
print(info03.title())
print(info03.upper())
print(info03.lower())
...等等

总结

首先字符串是不可变的，其次字符串的拼接很高效，最后字符串的格式化很常见！