Ask a FLOAT question-php Tutorial

Ask a FLOAT question $ usec: number of current microseconds, $ sec: current number of seconds list ($ usec, $ sec) explode (, microtime (); $ time1 (float) $ usec + (float) $ sec; list ($ usec, $ sec) explode (, microtime (ask a FLOAT question)
// $ Usec: number of current microseconds, $ sec: current number of seconds
List ($ usec, $ sec) = explode ('', microtime ());
$ Time1 = (float) $ usec + (float) $ sec;

List ($ usec, $ sec) = explode ('', microtime ());
$ Time2 = (float) $ usec + (float) $ sec;

Echo $ time2-$ time1;

The result outputs a number similar to this: 3.40938568115E-5.

Problem:
Print $ usec and $ sec separately, and output the following number: 0.95312700 1326693637
$ Time output: 1326693637.95
Why does $ time1-$ time2 output "3.40938568115E-5 "???

Thank you.


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Discussion

Reference:

You can customize the format.
PHP code

Echo sprintf ('%. 16f', $ time2-$ time1 );

I don't know why this happens by default...

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Because the value is too small to be represented by decimal places, it can only be represented by scientific notation.
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Because your $ time2-$ time1 value is too small, it is about 0.0000340938568115
In this way, the previous 0 values affect the accuracy display, so it is automatically changed to scientific notation.
3.40938568115E-5 is equivalent to 3.40938568115*10 ^-5
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Discussion

In fact, I mean:
$ Time1 and $ time2 are similar to the following numbers: 1326693637.95
Then they subtract two decimal places. why are there so many decimal places ??