发行新股

T x[size] size * sizeof(T) char buffer[size*sizeof(T)]

char T malloc new

int 0x1000 0x1004 0x1001

size * sizeof(T) + A - 1

T

size_t elementCount;
// padding to get native alignment for 1st element
T elements[elementCount];

size_t elementCount; // 4
char padding[16 - sizeof(elementCount)];
T elements[elementCount]; // naturally aligned

char x[size*sizeof(T)]; alignment alignment(2)

sizeof(int) == 4

int *intarray = new int[2];        // 8 bytes
char *charptr = (char *)intarray;  // legal reinterpret_cast
charptr += 1;                      // still 7 bytes available
*((int*)charptr) = 1;              // BAD!

int

char ra[8];
int *intptr = reinterpret_cast<int*>(ra);
intptr[0] = 1;  // BAD!

ra

char ra = new char[8];
int *intptr = reinterpret_cast<int*>(ra);
intptr[0] = 1;  // NOT BAD!

new

struct foo {
    char first[1];
    char second[8];
    char third[3];
};

second

std::size_t

alignment