跟着文档学python（二）：time.time() 与 time.clock() 的对比与总结

一，两个函数的文档：

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()

返回从纪元（1970.1.1）至今的秒数。虽然这个函数的返回值永远为浮点数，但并不是所有系统提供的秒数都会精确到小数点以后。一般情况下这个函数的返回值不会小于它上一次被调用的返回值，除非系统时钟在两次调用之间发生了重置。

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，将当前的处理器时间以浮点数的形式返回，单位为秒。它的精确度（准确地说是“处理器时间”的精确度）取决于同名的C函数，无论如何，这个函数是python关于时间计算的标尺。

WINDOWS中，第一次调用，返回的是进程运行的实际时间。而第二次之后的调用是自第一次调用以后到现在的运行时间。（实际上是以WIN32上QueryPerformanceCounter()为基础，它比毫秒表示更为精确）

二，用法及总结

1，在Windows中，time.clock()更精确；

2，这两个函数不可以混合使用；

（未完待续）

参考：Python time clock()方法 | 菜鸟教程