CODEWITHSUNDEEP
cpointers
tzippy
tzippy

Reputation: 6638

Pointer arithmetic with a void pointer

I was wondering if theres a better way instead of casting a void pointer to uint8_t, then do arithmetic based on an offset, then cast it to uint32_t, then dereference it to get a 4byte value at that exact offset.

void * foo = malloc(1024);
uint32_t myVar;

for(int i = 0; i < 10; i++)
{
  myVar = *((uint32_t*)((uint8_t *) foo + nOffset));
  nOffset += 100;
}

Upvotes: 0

Views: 205

Answers (1)

glglgl
glglgl

Reputation: 91017

You would better simply stay within one "domain" of pointer arithmetic.

You should do uint32_t * foo = malloc(1024);

and then either

myVar = foo + nOffset / sizeof(*foo);
nOffset += 100;

or

myVar = foo + nOffset;
nOffset += 100 / sizeof(*foo);

for advancing by 100 bytes at each step.

Upvotes: 1

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