Question

I have 2 questions:

This code:

   struct employee
   {
      char name[20];
      int married :1;
   };

How many does married take in memory?

And if I have multiple bit-sized fields Does it good to put them in the same variable of keep them individual?

like:

struct employee
{
 char name[31];
 int married :1;
 int manager :2;
 int children :4;
};

Or

struct employee
{
 char name[31];
 int flage; /* one bit for married, one for manager, and 4 bits for children */
};

Which one is better in memory usage and why???

Answer 1

When you use int flage for storing information regarding married manager and children, it MAY take 2 bytes of memory for one object, and every time you have to access a particular information you have to perform bitwise operations on the flage variable. This will thus require some processing.

By using a bitfield, like int married:1; (you better use unsigned int), that means it MAY take just 1 byte of memory, therefore you MAY save memory (supposing your struct is not padded). As a bonus, you can access its bits directly.

So it should be better approach regarding memory and processing.