Question

I need to store boolean information for around 10000 variables. First I thought of using a bool array arr[10000] but it takes 40000 bytes. But I need to store this information in a memory efficient way. Maybe using bit manipulation? Also another thing that I need to store it globally and allocate it dynamically also. Can you please help me with this?

Answer 1

You could do:

vals = new char[(len+7)/8];
// To access
vals[i/8] & 1 << (i % 8)
// To set
vals[i/8] |= 1 << (i % 8);
// To clear
vals[i/8] &= ~(char)(1 << (i % 8));

Though to be the fastest, you should use whatever the word size is sized chunks. So on a 32-bit computer:

vals = new uint32_t[(len+31)/32];
// To access
vals[i/32] & 1 << (i % 32)
// To set
vals[i/32] |= 1 << (i % 32);
// To clear
vals[i/32] &= ~(uint32_t)(1 << (i % 32));