Why is a floating point value, such as 3.14, considered by default in MSVC?

Question

Why do I need to put 3.14f instead of 3.14 to disable all of these warnings? Is there a common reason for this?

Answer 1

What the C ++ (and C) standard decided. Floating point literals are of type double, and if you need them to float, you suffix them with f . There seems to be no specific reason why, but I would suggest that a) for compatibility with C and b) a trade-off is between accuracy and storage.

2.13.3 Floating literals A type of lithographic document is double, unless explicitly specified by a suffix. the suffixes f and F indicate float, the suffixes l and L indicate a long double. If the scale value is not in the range of the represented values ​​for its type, the program is poorly formed.

Answer 2

C and C ++ prefer double swimming in several ways. As you noticed, fractional literals are double unless floats are explicitly made. In addition, floats cannot be passed to varargs; they always go up to double (in the same way, char and short go up to int in varargs).

It is probably best to think of a float as an abbreviated double rather than a double being an extended float . That is, double is the preferred floating-point type, and float used whenever a smaller version of double is required for a particular case. What is closest I know to the sequential reason, and then the rule makes sense, even if you happen to need a smaller version.

Answer 3

This is not MSVC specific, it is required by locale.

I would suggest that it makes sense not to reduce the accuracy unless explicitly requested, so the default value is double.

6 significant digits of accuracy, which provides floating single-point accuracy, are rarely sufficient for general use and, of course, on a modern desktop processor will be used as manual coded optimization, where the writer has determined that this is sufficient and necessary; therefore, it makes sense that an explicit visible marker is required to indicate a literal with one precision.

Answer 4

This is probably the standard in the world of C. Double is preferable because it is more accurate and you probably won't see any performance differences. Read this post .

Answer 5

Because a double can approach 3.14 much better than a float , maybe? Here are the exact values:

3.140000000000000124344978758017532527446746826171875 ( double )

3.1400001049041748046875 ( float )