Data types in C++

[lynnajoe]

Hi,

I was wondering if anyone has ever heard of "mixed" as a data type along the lines of int, double etc? I came across this on a website. Sorry to post what you already know but I wanted to get the point across that they are saying this is a data type. I am new obviously but I found it interesting.

char
Character and/or small integer.
1byte
-128 to 127(unsigned: 0 to 255)

int
Integer
4bytes
-2147483648 to 2147483647(unsigned:0 to 4294967295)

bool
Boolean value, can take two values "True" or "False
1byte
True or False

float
Floating point number
4bytes
3.4e +/- 38 (7 digits)

wchar_t
Wide character
2bytes
1 wide character

mixed
Any type
Unknown
Unknown


Thank you,

Lynnajoe

[Danny]

No, mixed is not a standard built-in type. It's most likely a union that represents a variant, that is an unspecified piece of memory whose exact type is determined at runtime based on a type-field or some other form of encoding.

[lynnajoe]

Hi,

Thank you. I was wondering because they had it grouped with the other data types as if it was the same. I tried it and I believe you are correct that it is a union. The information was very misleading.

[vijayan]

The information was very misleading.

It is also misleading (wrong) when it specifies the precise sizes and ranges of intrinsic data types; for example:

int
Integer
4bytes
-2147483648 to 2147483647(unsigned:0 to 4294967295)

The C++ standard does not specify the exact sizes or ranges of the intrinsic data types. (Only their relative sizes are specified.) The set of generic fundamental types have implementation-defined limits (with minimum guarantees). The size and range of the basic types can be accessed via std::numeric_limits<> in the header <limits>. For example, a byte could be 32 bits (or more), and each of char, short, int, and long could be one byte. (A byte isn't necessarily an octet; it is of the same size as a char.)

With C++0x, the standard header <cstdint> (<boost/cstdint.hpp> can be used for for C++98), the library additionally provides a set of fixed-sized integral types (for example std::int32_t).