全局结构是在堆栈上还是在堆上分配的？

Question

I am writing in an environment where I am not allowed to allocate new memory after program startup, nor am I allowed to make operating system calls. In tracking down a page fault error (likely caused by inadvertently violating one of the above) the question occurs to me (since this bit me in the butt with std strings)

Is a global/local struct allocated on the stack or heap? For example:

If this statement is in the global scope

struct symbol {
    char blockID;
    int blockNum;
    int ivalue;  
    double fvalue;
    int reference;
    bool isFloat, isInt, isRef;
    int symbolLength;
} mySymbol;

where is the memory for it allocated?

Answer 1

It's implementation-defined (the C++ standard doesn't really talk about stack and heap).

Typically, objects with static storage duration (such as globals) will end up in a special segment of address space that is neither stack nor heap. But the specifics vary from platform to platform.

Answer 2

In C++, unlike in C#, struct makes few differences with class . A struct is a class whose default visibility is public. Whether the allocation is performed on the stack or in the heap depends on the way you allocate your instance

class A;

void f()
{
 A a;//stack allocated
 A *a1 = new A();// heap
}