switch analogy

Question

C++ / C#

There is a long, long switch for a thousand-plus cases on the packet parser.
Attention, the question is:
is this thing more efficient:

char k;
typedef void(*fptr)();
fptr t[65535];


void a(){k='a';}

void b(){k='b';}

void c(){k='c';}

void* (func)();

void main ()
{
        memset(t,0,sizeof(t));
  t[0]=&a;
  t[1]=&b;
  t[2]=&c;
  unsigned short i;
  cin>>i;
//ключевой кусок
  t[i] ? t[i]() : t[i];
  printf("k=%c",k);
//конец ключевого куска
  _getch();
}

If not, what can you advise?

UPD thanks to ixSci for helping and simplifying the code.

Answer 1

Your “thing” is more efficient both in terms of design and speed. switch is generally not the best choice.
Only I would replace it

if(t[i]!=NULL){
        g =(void(*)()) t[i];   
        g();   //или g();   - аналогично
        printf("k=%c",k);
    }

on this

t[i] ? t[i]() : t[i];

Answer 2

Most likely or equally, or the switch is more effective.
The performance of the switch does not depend on the size, since there is still a jump table there.
If the goal is to improve performance, I would advise starting with profiling and finding really slow places; replacing the switch with an array of functions will do nothing in this regard.

Answer 3

1) what kind of efficiency is the question about: speed, code size, code clarity?
2) the proposed code is unambiguously supplemented by checking the admissible range i.

Answer 4

Correct if is always faster than switch

Answer 5

According to the tests that I conducted, a well-built elseif (with the most common cases on top) worked on large volumes much faster than a similar switch, which cannot be set to the “most frequent options”
(poked in the wrong place, the answer is in the thread of the second comment)