topic Pointer or array? in 8-bit Microcontrollers

Pointer or array?

roberto_m — Wed, 14 Apr 2010 19:48:58 GMT

In an 8-bit mcu, is better in function arguments use pointer or value?

Re: Pointer or array?

kef — Wed, 14 Apr 2010 20:36:26 GMT

Pointer of course. Passing array by value you rise stack space requirements. Also passing array by value slows down execution, because it takes time to copy array from source to the stack.

Re: Pointer or array?

bigmac — Wed, 14 Apr 2010 23:39:35 GMT

Hello Roberto,

My understanding is that, when a function uses an array name as an argument, the contents of the array are not passed to the function, but a pointer to the first element of the array is automatically passed instead. Therefore I would suspect that passing an array name, or explicitly passing a pointer should give similar results.

Regards,

Mac

Re: Pointer or array?

Lundin — Thu, 15 Apr 2010 21:21:42 GMT

Correct. There is no way to pass an array by value as a function parameter in the C language.

void func (int* x); /* this is a pointer */

void func(int x[]); /* this is a pointer */

void func(int x[10]); /* this is a pointer */

In all 3 cases above, a pointer is passed on the stack, and nothing else.