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No. Static memory is allocated at compile time. Static variables are allocated within the program's data segment which is a physical part of the executable. When you load the executable into memory, the operating system sets aside enough memory for the entire executable and copies it, byte for byte, into that memory. So when the program is executed, the data segment is already allocated.
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Is declaration of variables allocated memory?
Constants, static variables and global variables are allocated in the program's data segment at compile time. Local variables are allocated on the stack at runtime. Variables cannot be allocated on the heap, you must use a constant, static variable, global variable or local variable to store the start address of a dynamic memory allocation. The variable must be a raw pointer or a reference handle (a smart pointer).
Difference between dynamic and static memory allocation?
Static memory allocation is memory allocated on the "stack" and cannot be resized after the initial allocation, while dynamic memory allocation is memory allocated in the "heap", and can be dynamically expanded and shrunk as necessary.
Why memory is divided into initialized and uninitialized areas?
The program's data segment. This area of memory is allocated by the linker and is used to store the program's global variables, static variables, static arrays and constants. Constants are always initialised, as are static variables, but global variables and static arrays need not be initialised.
What do you mean by free store in c plus plus?
The free store in any language refers to the heap. The three main areas of memory that all C++ programs use are the heap, the call stack and static memory. Static memory is allocated at compile time, is fixed-length and caters for all static variables, global variables and constant variables. Call stacks are also fixed-length and are allocated to threads of execution as they are instantiated (each thread has its own stack). The free store or heap is essentially all remaining memory accessible to our program. To use the heap we must request memory from the system as it is required and release it when we are finished with it.
C memory model?
Memory Organization for a process -------------------------------------------- CODE SEGMENT: contains executable code DATASEGMENT:contains static and global variable HEAP SEGMENT:Dynamically allocated variables will be in heap STACK SEGMENT:For local or automatic variables PREM G premgnath@gmail.com
Is declaration of variables allocated memory?
Constants, static variables and global variables are allocated in the program's data segment at compile time. Local variables are allocated on the stack at runtime. Variables cannot be allocated on the heap, you must use a constant, static variable, global variable or local variable to store the start address of a dynamic memory allocation. The variable must be a raw pointer or a reference handle (a smart pointer).
Difference between dynamic and static memory allocation?
Static memory allocation is memory allocated on the "stack" and cannot be resized after the initial allocation, while dynamic memory allocation is memory allocated in the "heap", and can be dynamically expanded and shrunk as necessary.
Why memory is divided into initialized and uninitialized areas?
The program's data segment. This area of memory is allocated by the linker and is used to store the program's global variables, static variables, static arrays and constants. Constants are always initialised, as are static variables, but global variables and static arrays need not be initialised.
What is the difference between static and dynamic memory?
There is no such thing as dynamic memory, but we often use the term to mean non-static memory. Static memory is where all constant variables, global variables and static variables are allocated in static memory. Static memory is a contiguous block of memory of fixed length divided into two sections: initialised memory and uninitialised memory. Initialised variables and constants are allocated to the initialised section and are stored as a bitmap image in the executable itself. Uninitialised variables are allocated in the uninitialised section which is typically a block of zero-initialised memory. No bitmap image is required for uninitialised memory, only its length need be stored in the executable. The compiler can determine the amount of memory required for each constant and variable. Non-static memory is essentially all other memory used by a program. Every thread has its own call stack allocated as each thread is instantiated and released as each thread is destroyed. All stacks are fixed-length (determined at design time). The call stack is used to store local variables, automatic variables and temporary variables, as well as to implement exception handling. The heap (or free store) is essentially all other memory available to the program and is used to instantiate all anonymous variables. The heap is what we generally mean by dynamic memory because anonymous variables are created and destroyed as and when they are required at runtime. Since we cannot refer to an anonymous variable by name (being anonymous means they have no name), we must refer to them solely by their address. This means we must use pointer variables to store those addresses. If we have a large number of anonymous variables of the same type to keep track of, then we typically allocate them in contiguous memory and maintain a single pointer to the start of the allocation. This single pointer allows us to access the memory just as we would a built-in array. We also need to keep track of how many variables (elements) are allocated in the array to avoid buffer overruns. This allows us to easily allocate and release any number of anonymous variables at runtime. However, in C++ we rarely use "dynamic memory" directly. Although necessary in C Programming, C++ programmers prefer to use resource handles or "smart" pointers instead. In this way the language itself handles the underlying memory allocations for us, ensuring that memory is allocated and released in a timely manner, and thus minimising the risk of creating resource leaks -- a common problem with low-level C programming. The C++ std::vector is an example of a resource handle and most non-trivial C++ programs will include one or more std::vector<std::unique_ptr<T>> variables to keep track of any number of pointers to type T objects.
How is memory allocated to objects in c plus plus?
In C++ we can allocated objects in static memory, on the stack, or on the heap. It's all the same memory (RAM), the only difference is in when it is allocated. Static memory is allocated at load time and contains all constant variables, static variables and global variables. Static objects are initialised at compile time which creates a bitwise image of each object's initial representation. The image is embedded in the executable and is copied to the allocated memory at load time. If a static object constructor body contains any additional initialisation code that cannot be optimised away by the compiler, that code is execute at runtime. It is vital that static object constructors do not throw.Local objects and function arguments are allocated on the stack at runtime. Every thread of execution has its own stack and the memory is allocated when each thread is instantiated. Stacks are fixed size (determined at compile time) and extend downwards from the highest address while a stack pointer keeps track of the top of the stack (the highest available address). When a function is invoked by a thread, the stack pointer is adjusted, creating a stack frame to store the function's return address, its arguments and its local objects. The size of each stack frame can be determined at compile time.All other objects are allocated on the heap at runtime. We often refer to these objects as dynamic objects. A dynamic object is constructed via operator new which allocates sufficient memory from the free store to accommodate the object's representation. If successful, the object constructor then initialises the memory. If memory cannot be allocated, operator new will either throw a std::bad_alloc exception or will return a nullptr, depending on which overload was invoked. Every class of object has implicit new and delete operators which can be overridden. The default operator new implementations will request memory from the system on an as-required basis while the delete operator releases that memory back to the system. If we wish to provide our own memory management facility, we can allocate uninitialised ("raw") memory at runtime using the global operator new and then construct objects within that memory. This can improve performance by reducing the number of allocation requests we need to make from the system. Once raw memory is allocated we can freely use it as we see fit, however we must manually ensure no two objects occupy the same address space and we must ensure the memory is released as soon as we are finished with it.
What is dynamic mamory?
Dynamic memory refers to memory that is allocated and deallocated during program execution, as opposed to static memory which is allocated at compile time. In C and C++, dynamic memory allocation is done using functions like malloc() and free(), allowing for flexibility in managing memory resources at runtime. However, improper use of dynamic memory can lead to memory leaks or segmentation faults.
What do you mean by free store in c plus plus?
The free store in any language refers to the heap. The three main areas of memory that all C++ programs use are the heap, the call stack and static memory. Static memory is allocated at compile time, is fixed-length and caters for all static variables, global variables and constant variables. Call stacks are also fixed-length and are allocated to threads of execution as they are instantiated (each thread has its own stack). The free store or heap is essentially all remaining memory accessible to our program. To use the heap we must request memory from the system as it is required and release it when we are finished with it.
C memory model?
Memory Organization for a process -------------------------------------------- CODE SEGMENT: contains executable code DATASEGMENT:contains static and global variable HEAP SEGMENT:Dynamically allocated variables will be in heap STACK SEGMENT:For local or automatic variables PREM G premgnath@gmail.com
Can variables be changed?
A static variable is one which is not stored on the stack but in the memory of the program. Static variables can be changed.
Can we declare register variable as global?
Globals and statics are both allocated in static memory. Locals are allocated on the stack.
Diffference between dynamic memory alllocation and static memory alllocation?
Static memory is allocated at program load time using information found in the program's data segment. Static memory is fixed size and stores all the program's constants, global variables and static variables. Dynamic memory includes both the call stack and the heap (free store). Every process has at least one thread (the main thread) and each thread is allocated its own stack. A thread's stack is allocated when the thread is instantiated and released when the thread terminates. The stacks are fixed size and are used to store function local variables, function return addresses and exception handlers. Heap memory is what we generally term dynamic memory, which is memory that is allocated and released as and when required. Since stack memory is pre-allocated, it is quicker to access since memory is allocated and released simply by adjusting the pointer that marks the top of the stack. However, because it is fixed size, it has limited capacity. We try to use the stack as much as possible for performance, but the limited capacity means it is only useful for relatively small allocations, including non-static (local) fixed size arrays. However, the stack size can be adjusted at compile time if we require more (or less) than is provided by default.
What is the difference between a static variable a global variable and a local variable?
A static variable is a variable allocated in static storage. A local variable is a variable declared inside a function. A global variable is a variable declared outside of any class or function. Note that local variables and global variables can both be allocated in static storage.
