python3时间

1、介绍

time模块是python的内部模块。用于获取系统时间，格式化输出，将参数解析为时间等。

2、函数

(1)获取当前时间

print(time.time(), type(time.time()))

• 返回float类型，1670592065.0852547形式，单位为秒

(2)获取当前时间

print(time.time_ns(), type(time.time_ns()))

• 返回int类型，1670592289035206400形式 ，单位为纳秒。1秒=10^9纳秒

(3)休眠

time.sleep(5)
print(123)

• 休眠，线程暂停执行，单位秒

(4)strftime

• 格式化

    %Y  Year with century as a decimal number.
    %m  Month as a decimal number [01,12].
    %d  Day of the month as a decimal number [01,31].
    %H  Hour (24-hour clock) as a decimal number [00,23].
    %M  Minute as a decimal number [00,59].
    %S  Second as a decimal number [00,61].
    %z  Time zone offset from UTC.
    %a  Locale's abbreviated weekday name.
    %A  Locale's full weekday name.
    %b  Locale's abbreviated month name.
    %B  Locale's full month name.
    %c  Locale's appropriate date and time representation.
    %I  Hour (12-hour clock) as a decimal number [01,12].
    %p  Locale's equivalent of either AM or PM.

示例：

print(time.strftime("%Y%m%d"))#20221103

(5)基于float数值获取时间

t = time.time()
print(t, type(t))
t2 = time.localtime(t)
print(t2)
print(t2.tm_year)
print(time.strftime('%Y', t2))
"""
1682606149.9445274 <class 'float'>
time.struct_time(tm_year=2023, tm_mon=4, tm_mday=27, tm_hour=22, tm_min=35, tm_sec=49, tm_wday=3, tm_yday=117, tm_isdst=0)
2023
2023
"""

3、计算程序运行时间

（1）

t1 = time.time_ns()
for i in range(1000):
    s = i
    print(s)
    time.sleep(0.001)
t2 = time.time_ns()
# 运行过程的时间，单位秒
print((t2-t1)/(10**9)) # 约16秒多

（2）

t1 = time.time()
for i in range(1000):
    s = i
    print(s)
    time.sleep(0.001)
t2 = time.time()
# 运行过程的时间，单位秒
print(t2-t1) # 约16秒多，float类型