Namespaces
Variants
Views
Actions

Memory model

From cppreference.com
< cpp‎ | language
 
 
C++ language
General topics
Flow control
Conditional execution statements
if
Iteration statements (loops)
for
range-for (C++11)
Jump statements
Functions
Function declaration
Lambda function expression
inline specifier
Dynamic exception specifications (until C++17*)
noexcept specifier (C++11)
Exceptions
Namespaces
Types
Specifiers
decltype (C++11)
auto (C++11)
alignas (C++11)
Storage duration specifiers
Initialization
Expressions
Alternative representations
Literals
Boolean - Integer - Floating-point
Character - String - nullptr (C++11)
User-defined (C++11)
Utilities
Attributes (C++11)
Types
typedef declaration
Type alias declaration (C++11)
Casts
Implicit conversions - Explicit conversions
static_cast - dynamic_cast
const_cast - reinterpret_cast
Memory allocation
Classes
Class-specific function properties
explicit (C++11)
static
Special member functions
Templates
Miscellaneous
 
 

Defines the semantics of computer memory storage for the purpose of the C++ abstract machine.

The memory available to a C++ program is one or more contiguous sequences of bytes. Each byte in memory has a unique address.

[edit] Byte

A byte is the smallest addressable unit of memory. It is defined as a contiguous sequence of bits, large enough to hold

  • the value of any UTF-8 code unit (256 distinct values) and of
(until C++23)
(since C++23)

Similar to C, C++ supports bytes of sizes 8 bits and greater.

The types char, unsigned char, and signed char use one byte for both storage and value representation. The number of bits in a byte is accessible as CHAR_BIT or std::numeric_limits<unsigned char>::digits.

[edit] Memory location

A memory location is

Note: Various features of the language, such as references and virtual functions, might involve additional memory locations that are not accessible to programs but are managed by the implementation.

struct S
{
    char a;     // memory location #1
    int b : 5;  // memory location #2
    int c : 11, // memory location #2 (continued)
          : 0,
        d : 8;  // memory location #3
    struct
    {
        int ee : 8; // memory location #4
    } e;
} obj; // The object “obj” consists of 4 separate memory locations

[edit] See also

C documentation for Memory model