Differentiate between float and double

Question

//assume there is no Print(double dValue)
void Print(unsigned int nValue);
void Print(float fValue);
Print(3.14159);

Shouldn't the Print(3.14159) match with Print(float) ?

Instead of it, this code lead to an ambiguous match

Is 3.14159 a double ?
How to differentiate between float and double ?

What do you mean with ambiguous match? Do you get compiler error or strange behaviors? — gcswoosh, Apr 05 '15 at 00:45
Check this out: http://stackoverflow.com/questions/2386772/difference-between-float-and-double — sam, Apr 05 '15 at 00:45

score 3 · Accepted Answer · answered Apr 05 '15 at 00:46

3

Is 3.14159 a double ?

Yes, it is.

How to differentiate between float and double ?

Use 3.14159f to make the constant a float. Use 3.14159 to make the constant a double.

answered Apr 05 '15 at 00:46

R Sahu

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score 1 · Answer 2 · answered Apr 05 '15 at 00:45

3.14159 numeric literal is a double, not a float. C++ has two choices:

Convert double to unsigned int, and call the first overload
Convert double to float, and call the second overload

Both choices require the same number of conversions, to C++ issues an error.

You can fix this by appending F to the end of the literal:

Print(3.14159F);
//           ^

Now the first choice still requires a float to unsigned int conversion, while the second choice can proceed without conversion; hence, the second overload "wins".

Differentiate between float and double

2 Answers2