PYTHON字符串 *** 作 & format格式化 & 时间time库

字符串处理函数

1、len(x) 返回字符串的长度

len("1234567")
7

2、str(x) 任何类型转换为字符串

str(1.2345)
'1.2345'
str([1,2])
'[1, 2]'

'1 + 1 = 2' + chr(10004)
'1 + 1 = 2✔'

3、hex(x)十六进制， oct(x)八进制

hex(425)
'0x1a9'
oct(425)
'0o651'

4、 str(u) 返回Unicode编码对应的字符， ord(x)返回字符x的Unicode编码

在这里插入代码片

eg：遍历星座字符：

for i in range(12):
    print(chr(9800 + i), end="")
♈♉♊♋♌♍♎♏♐♑♒♓

字符串处理方法

1、str.lower() 或者str.upper 全部字符小写或者大写

"adCDHGDE".lower()
'adcdhgde'
"adCDHGDE".upper()
'ADCDHGDE'

2、str.split()分割字符串返回列表

"a,b,c".split(",")
['a', 'b', 'c']

3、str.count() 字串出现的次数

"an apple a day".count("a")
4

4、str.replace(old, new)字符串替换

"hello".replace('o','o world')
'hello world'

5、str.center(width[, fillchar])居中

"python".center(20, "=")
'=======python======='

7、str.strip(char)去掉char中出现的字符

"--  python--".strip(' -np')
'ytho'

8、str.join(iter)在iter变量除最后一个元素外每个元素后加str

",".join('123456')
'1,2,3,4,5,6'

format格式控制

",".join('123456')
'1,2,3,4,5,6'
"{0:=^20}".format("PYTHON")
'=======PYTHON======='
"{0:*>20}".format("PYTHON")
'**************PYTHON'
"{0:20}".format("PYTHON")
'PYTHON              '
"{0:,.2f}".format(1234567.789)
'1,234,567.79'
"{0:b},{0:c},{0:d},{0:o},{0:x},{0:X}".format(456)
'111001000,Lj,456,710,1c8,1C8'
"{0:e},{0:E},{0:f},{0:%}".format(3.14)
'3.140000e+00,3.140000E+00,3.140000,314.000000%'

时间

import time
time.ctime()
'Mon May  9 23:48:53 2022'
time.time()
1652111340.4037457
time.gmtime()
time.struct_time(tm_year=2022, tm_mon=5, tm_mday=9, tm_hour=15, tm_min=49, tm_sec=50, tm_wday=0, tm_yday=129, tm_isdst=0)
t = time.gmtime()
time.strftime("%Y-%m-%d %H:%M:%S", t)
'2022-05-09 15:52:31'

timeStr = '2022-05-09 15:52:31'
time.strptime(timeStr, "%Y-%m-%d %H:%M:%S")
time.struct_time(tm_year=2022, tm_mon=5, tm_mday=9, tm_hour=15, tm_min=52, tm_sec=31, tm_wday=0, tm_yday=129, tm_isdst=-1)

计时

start = time.perf_counter()
end = time.perf_counter()
end - start
5.154938300023787

休眠

def wait():
    time.sleep(4)

wait()