performance - Most efficient pointer arithmetic type in c -

i assume internal casting happens when write: arr[i] (which equivalent *(arr+i)). because i can example short, int or long or unsigned variant of of these three.

so question simple: type should i no internal conversion takes place? code can run efficiently?

crude guess: size_t?

it's unlikely make significant difference performance. in case, should using type that's semantically correct, not trying make premature optimizations things aren't going matter. in case of indices, size_t smallest type that's a priori correct, may able away smaller types if know array you're working bounded. though should use size_t safe.