CODEWITHSUNDEEP
c#mathfloor
Sridhar
Sridhar

Reputation:

Why does Math.Floor(Double) return a value of type Double?

I need to get the left hand side integer value from a decimal or double. For Ex: I need to get the value 4 from 4.6. I tried using Math.Floor function but it's returning a double value, for ex: It's returning 4.0 from 4.6. The MSDN documentation says that it returns an integer value. Am I missing something here? Or is there a different way to achieve what I'm looking for?

Upvotes: 127

Views: 65998

Answers (5)

user3306645
user3306645

Reputation: 1

Convert.ToInt32(Math.Floor(Convert.ToDouble(value)))

This will give you the exact value what you want like if you take 4.6 it returns 4 as output.

Upvotes: -1

Jon Skeet
Jon Skeet

Reputation: 1500515

The range of double is much wider than the range of int or long. Consider this code:

double d = 100000000000000000000d;
long x = Math.Floor(d); // Invalid in reality

The integer is outside the range of long - so what would you expect to happen?

Typically you know that the value will actually be within the range of int or long, so you cast it:

double d = 1000.1234d;
int x = (int) Math.Floor(d);

but the onus for that cast is on the developer, not on Math.Floor itself. It would have been unnecessarily restrictive to make it just fail with an exception for all values outside the range of long.

Upvotes: 171

Jon Seigel
Jon Seigel

Reputation: 12401

If you just need the integer portion of a number, cast the number to an int. This will truncate the number at the decimal point.

double myDouble = 4.6;
int myInteger = (int)myDouble;

Upvotes: 5

Neil N
Neil N

Reputation: 25258

According to MSDN, Math.Floor(double) returns a double: http://msdn.microsoft.com/en-us/library/e0b5f0xb.aspx

If you want it as an int:

int result = (int)Math.Floor(yourVariable);

I can see how the MSDN article can be misleading, they should have specified that while the result is an "integer" (in this case meaning whole number) it is still of TYPE Double

Upvotes: 13

plinth
plinth

Reputation: 49189

Floor leaves it as a double so you can do more double calculations with it. If you want it as an int, cast the result of floor as an int. Don't cast the original double as an int because the rules for floor are different (IIRC) for negative numbers.

Upvotes: 0

Related Questions