difference between vet[] and *vet

Question

When I send a vector to the function, in the arguments.. what’s the difference between putting

void funcao(int vet[])

and

void funcao(int *vet)

Answer 1

What’s the difference between void funcao(int vet[]) { /* ... */ } and void funcao(int *vet) { /* ... */ }?

Absolutely none.
The two shapes are 100% identical.

Note that in C, it is impossible to pass arrays as parameters to a function (and that the compiler automatically converts to a pointer to the first element). With that in mind, the second option seems to correspond better to reality.

Answer 2

Your question is whether there’s a difference between vet[] and *vet. Well, the answer is no.

According to the booklet IME USP:

Vectors

Vectors are indexed structures used to store data of the same type: int, char, float or double. For example, the statement
int v[80]; /∗ declara um vetor de inteiros de nome v com 80 casas ∗/

Each home of the vector v (that is to say, v[0], v[1], ..., v[79]) is a whole. In addition, each house has an address associated (ie, &v[0], &v[1], ..., &v[79]).

One question we could ask is how a vector gets stored in memory. The organization of variables in memory depends on how the operating system does memory management. In general, to be more efficient, the operating system tends to place the oats Vari successively. Thus, the vector allocation in the memory is made successively, that is, as illustrated in the figure above: v[0] before v[1], that in turn before v[2] and so on. Thus, the variables declared as

int v [80]; /∗ declara um vetor de inteiros de nome v com 80 casas ∗/
int n , m;

could be allocated successively as

In the C language there is no check of indexes outside the vector. Who should control the correct use of indexes is the programmer. In addition, access using a wrong index may cause access to another variable in memory. In the above example, v[80] would access variable n. If access to memory is improper you receive the message "Segmentation fault".

Vectors and Pointers

The implementation of vectors in C is very interconnected with the pointers aiming to facilitate the manipulation vector. Consider the following variable statement:

int v[80]; /∗ declara um vetor de inteiros de nome v com 80 casas ∗/
int *p;

that allocates to Mem:

We can use normal syntax to make a pointer point to a vector home:

p = &v [2]; /∗ p aponta para a casa de índice 2 de v ∗/

But we can use the special syntax for pointers and vectors, together with operations for pointers:

• We can make a pointer point to the beginning of the v vector by doing
  p = v;

  It is the only situation where the vector name makes sense without the brackets. The above command is equivalent to do p = &v[0];

• We can use vector syntax (nome_do_vetor[índice]) with the pointer. So, if we do
  p = v;
  we can access the element that is in the house i of v doing p[i], that is, both p[i] and v[i] access the box i of vector v. Example:

i = 3;
p = v ; /∗ p aponta para v[0]. Equivale a fazer p = &v[0] ∗/
p [ i ] = 4; /∗ equivale a fazer v[i] = 4 ∗/

But if we do
p = &v [3];

then, p[0] is the element v[3], p[1] is the element v[4], p[2] is the element v[5], and so on.

• We can do some operations with pointers. Consider the following statement:

int ∗p , ∗q , n , v[50];
float ∗x , y[20];

1. When we add 1 to a pointer to int (for example, p) it points to the memory address just after the memory reserved for this integer. Example, if p = &v[4], then p+1 is the address of v[5], p+2 is the address of v[6], p+i is the address of v[4+i].
   Thus, ∗p (goes where the p is pointing) is the v[4]. Therefore, v[4] = 3 is the same thing as do ∗p = 3. Like p+1 is the address of v[5], then ∗(p+1) is v[5]. Thus, v[5] = 10 is the same thing as doing ∗(p+1) = 10.

2. If we add 1 to a float pointer (for example x) it advances to the address after this float. For example, if x=&y[3], then x+1 is the address of y[4] and x+i is the address of y[3+i].

3. Adding or subtracting an integer from a pointer:

p = &v [22]; q = &v [30];
p = p − 4 ; q++;
∗( p+2) = 3 ; ∗q = 4;

Which index of v gets 3? Which index of v gets 4?¹

Subtract two pointers:

p = &v [20]; q = &v [31];
n = q − p ; /∗ número inteiro : a diferença entre os índices, neste caso, 11. ∗

_{Source: IME.USP}