What's the difference between sizeof and alignof?

Question

What\'s the difference between sizeof and alignof?

#include 

#define SIZEOF_ALIGNOF(T) std::cout<< sizeof(T) << \'/\' << a         


        

Answer 1

The alignof value is the same as the value for sizeof for basic types.

The difference lies in used defined data types such as using struct; for an e.g.

typedef struct { int a; double b; } S;
//cout<

hence the sizeof value is the total size required for the given data type; and alignof value is the alignment requirement of the largest element in the structure.

Use of alignof : allocate memory on a particular alignment boundary.