why this output is different..??

[sanjay_zed]

hello guys..!!! am new to this phpfreak community...i hav faced some problem while getting on floating point nos addition..if i use

echo (int)((0.1+0.7))*10;

i am getting output as 7. If i remove (int), i would get output as 8..which is correct...

for any other possibilities like ((0.1+0.2))*10 am getting correct output as 3..pls guys help me on this wid proper reason....waiting for solution....

[Psycho]

Did you come up with that scenario on your own? Because that is the exact example in the manual as to why you should not cast an unknown fraction as an integer: http://php.net/manual/en/language.types.integer.php See the 2nd warning down on the page.

 

And there is a link in that warning as to the reason for the error: http://www.php.net/manual/en/language.types.float.php#warn.float-precision

 

[Emphasis added]

Additionally, rational numbers that are exactly representable as floating point numbers in base 10, like 0.1 or 0.7, do not have an exact representation as floating point numbers in base 2, which is used internally, no matter the size of the mantissa. Hence, they cannot be converted into their internal binary counterparts without a small loss of precision. This can lead to confusing results: for example, floor((0.1+0.7)*10) will usually return 7 instead of the expected 8, since the internal representation will be something like 7.9999999999999991118....

[micah1701]

Did you come up with that scenario on your own? Because that is the exact example in the manual

 

looks like the phpfreaks homework help hotline is now open for the semester.  LOL