Rounding exponential numbers results in ZERO

Question

I am trying to round the numbers like below

$num =  6.91227556465E-8;
echo round($num);

This results in 0 . I tied adding (float) before number , still I get zero , Expected result is 7.

Answer 1

RTM: http://php.net/round

float round ( float $val [, int $precision = 0 [, int $mode = PHP_ROUND_HALF_UP ]] )
                            ^^^^^^^^^^^^^^^^^^

You specified no precision, so a default of 0 decimal places is used, And since your number is actually

0.0000000691227etc...

you get 0 upon rounding, exactly as it should be.

php > echo round($num, 8);
7.0E-8

Note the extra parameter...