问题
I entered the following code (and had no compiling problems or anything):
float y = 5/2;
printf("%f\n", y);
The output was simply: 2.00000
My math isn't wrong is it? Or am I wrong on the / operator? It means divide doesn't it? And 5/2 should equal 2.5?
Any help is greatly appreciated!
回答1:
5 is an int and 2 is an int. Therefore, 5/2 will use integer division. If you replace 5 with 5.0f (or 2 with 2.0f), making one of the ints a float, you will get floating point division and get the 2.5 you expect. You can also achieve the same effect by explicitly casting either the numerator or denominator (e.g. ((float) 5) / 2).
回答2:
Why does 5/2 results in '2' even when I use a float?
Because you do not "use float". 5/2 is an integer division. Only its result (2) gets implicitly converted to a float to become a 2. (mind the dot).
回答3:
You should do proper type-casting .
float y = (float) 5/2
Program will treat the numbers as int.
It is dividing two ints and writing this to float. Hence, answer is 2.0
You must type cast
来源：https://stackoverflow.com/questions/40264523/why-does-5-2-results-in-2-even-when-i-use-a-float