Types

Every C++ Variable [1] needs a name and to know what kind of data [2] is stored as zero and ones in a portion of memory. We do not need to know where in memory the value is stored, because we can refer to the value by name, the identifier.

Primary Types

• Integer int
• Character char
• Boolean bool true or false
• Floating Point float
• Double Floating Point double
• Void void
• Wide Character wchar_t

Note: Like in C, the width of integers are not fixed

One Solution is to use a type with a fixed width, for example: when you need a 64bit integer type, use int64_t or uint64_t.

The nullptr keyword is usable without including the header <cstddef>, unless you must use std::nullptr_t.

Derived Types

• Function
• Array
• Pointer
• References

User-defined Types

• Class
• Structure
• Union
• Enum
• Typedef - typedef is to declare types

The identifier class in C++ is inspired by Simula (mathematicans). Structures are like Classes. Compared to Classes, they are identical, except Structs have public members and public inheritance by default.

typeid of <typeinfo> may return a mangled name, but can be used to debug.

1. c++ variables
2. types
3. type
4. integer

TypeCasts

A Cast is to convert between types:

• static_cast
• reintepret
• C-Style Cast
• Remove const-cast
• dynamic_cast

Static Cast

static_cast<int*>

compile-time cast, no runtime check.

Remove const-cast

Casting away the constness of a read-only const variable. [1]

C-Style cast

For Example (int) or (int*)

Warning: Think before you use C-Style Casts, prefer a static_cast which is explicit and easier to find

In C++ the C-Style Cast is accepted by the Compiler as long as a const_cast, static_cast and reintepret_cast or a combination is applicable [2]. This can for example led to Compiler-Portability Issues.

dynamic_cast

polymorphic cast on Runtime. For Example for downcasts (from base to derived class) and crosscasts (accross the object hierarchy) of pointers to polymorphic objects.

Beyond the C++ Standard Library: Boost provides also polymorphic casts [3].

1. const_cast
2. explicit_cast
3. boost: polymorphic_casts