Byte setting an unsigned short

Question

I'm trying to set the bytes in an unsigned short variable individually using memset:

#include <cstring>
#include <iostream>

int main()
{
  unsigned short test2; // 2 bytes

  std::cout << "size of test2: " << sizeof(test2) << std::endl;

  memset(&test2, 0, 2); 
  memset(&test2, 0x4D, 1);                                                               
  memset(&test2+1, 0x42, 1); 

  std::cout << "value: " << test2 << std::endl;

  return 0;
}

The output I'm getting is:

size of test2: 2
value: 77

77 is 0x4D. So for some reason it's not picking up the 0x42 that I'm trying to set on the second byte of the variable. Why is that?

Answer 1

&test2+1 will actually progress the address by sizeof(test2), which is 2, and move the pointer to out-of-range.

Try this with casting to char*:

#include <cstring>
#include <iostream>

int main()
{
  unsigned short test2; // 2 bytes

  std::cout << "size of test2: " << sizeof(test2) << std::endl;

  memset(&test2, 0, 2); 
  memset(&test2, 0x4D, 1);                                                               
  memset((char*)&test2+1, 0x42, 1); 

  std::cout << "value: " << test2 << std::endl;

  return 0;
}