跟着文檔學python（二）：time.time() 與 time.clock() 的對比與總結

一，兩個函數的文檔：

1，time.time():

time. time ( )

Return the time in seconds since the epoch as a floating point number. Note that even though the time is always returned as a floating point number, not all systems provide time with a better precision than 1 second. While this function normally returns non-decreasing values, it can return a lower value than a previous call if the system clock has been set back between the two calls.

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time. time ( )

返回從紀元（1970.1.1）至今的秒數。雖然這個函數的返回值永遠爲浮點數，但並非全部系統提供的秒數都會精確到小數點之後。通常狀況下這個函數的返回值不會小於它上一次被調用的返回值，除非系統時鐘在兩次調用之間發生了重置。

2，time.clock():

time. clock ( )

On Unix, return the current processor time as a floating point number expressed in seconds. The precision, and in fact the very definition of the meaning of 「processor time」, depends on that of the C function of the same name, but in any case, this is the function to use for benchmarking Python or timing algorithms.

On Windows, this function returns wall-clock seconds elapsed since the first call to this function, as a floating point number, based on the Win32 function QueryPerformanceCounter(). The resolution is typically better than one microsecond.

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time. clock ( )

在Unix 中，將當前的處理器時間以浮點數的形式返回，單位爲秒。它的精確度（準確地說是「處理器時間」的精確度）取決於同名的C函數，不管如何，這個函數是python關於時間計算的標尺。

WINDOWS中，第一次調用，返回的是進程運行的實際時間。而第二次以後的調用是自第一次調用之後到如今的運行時間。（其實是以WIN32上QueryPerformanceCounter()爲基礎，它比毫秒錶示更爲精確）

二，用法及總結

1，在Windows中，time.clock()更精確；

2，這兩個函數不能夠混合使用；

（未完待續）

參考：Python time clock()方法 | 菜鳥教程