python 獲取毫秒級時間問題的解決

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根據網上的一些說法，

在python裡獲取ms級系統時間可以通過以下方式獲取：

import datetime
print(datetime.datetime.now().microsecond)

但通過以下代碼測試，發現返回的並不是ms的值，而是us的值：

import datetime 
def getTime_ms():
    return (datetime.datetime.now().hour*3600 +\
            datetime.datetime.now().minute*60+\
            datetime.datetime.now().second )*1000+\
           datetime.datetime.now().microsecond/1000
 
def timetime():
    t = getTime_ms()
    while getTime_ms() - t < 500:
        pass
    a = getTime_ms()
    print(t, a, a- t) 
  
if __name__ == '__main__': 
    from timeit import timeit
    t = timeit('timetime()', 'from __main__ import timetime', number=1)
    print(t)

打印結果

(35460614, 35461114, 500) 0.499531984329

上面實驗不太直觀，換一個直觀點的：

def timetime():
    t1 = datetime.datetime.now()
    while 1:
        t2 = datetime.datetime.now()
        if (t2 - t1).microseconds >= 1:
            print(t2,t2.microsecond,t1,t1.microsecond,(t2-t1).seconds)
            break 
 
if __name__ == '__main__':
    from timeit import timeit
    t = timeit('timetime()', 'from __main__ import timetime', number=1)
    print(t)
    #print (datetime.datetime.now())

輸出

(datetime.datetime(2019, 4, 3, 10, 6, 20, 461882), 461882, datetime.datetime(2019, 4, 3, 10, 6, 20, 461863), 461863, 0) 7.10487365723e-05

def timetime():
    t1 = datetime.datetime.now()
    while 1:
        t2 = datetime.datetime.now()
        if (t2 - t1).microseconds >= 1000:
            print(t2,t2.microsecond,t1,t1.microsecond,(t2-t1).seconds)
            break 
 
if __name__ == '__main__':
    from timeit import timeit
    t = timeit('timetime()', 'from __main__ import timetime', number=1)
    print(t)
    #print (datetime.datetime.now())

輸出

(datetime.datetime(2019, 4, 3, 10, 13, 52, 76548), 76548, datetime.datetime(2019, 4, 3, 10, 13, 52, 75547), 75547, 0) 0.00104904174805

補充：Python datetime去除毫秒 返回當前時間

datetime模塊返回當前時間

import datetime
if __name__ == '__main__':
    a = datetime.datetime.now().replace(microsecond=0)
    print(a, type(a))

運算結果：

2020-05-22 12:13:42 <class ‘datetime.datetime’> Process finished with exit code 0

以上為個人經驗，希望能給大傢一個參考，也希望大傢多多支持WalkonNet。如有錯誤或未考慮完全的地方，望不吝賜教。

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