Pass vector of type struct as parameter of a function in C

I need to create a function that is in a .h file that generates random numbers n (user-defined and passed by parameter in function), and fill the set b with the generated values.

tConj.cpp file

TConj a,b,c,d;
    int elemento, i,op;
    long unsigned num;
    if (op==6){

    int num;
    printf("Quantidade de elementos a ser gerado: ");
    scanf("%d",&num);

    b = GerarConjunto(num);
}

TConj.h file

struct TConj{
    int * elemento;
    int n;

};
TConj GerarConjunto(int n){

TConj vet;
vet.elemento = (int *) malloc(10*sizeof(int));
int var;    

for (int i=0;i<n;i++){
    srand(time(NULL));
    var = rand()%n;
    vet.elemento[i] = var;
}

return vet;
}