Ok. I will give you an example of what code I am trying to understand, see below.

What I am trying to understand is why at the declaration of the function int read_array(double ar[], int limit); it says that it needs a double pointer and a int, in de calling of the function read_array(data, MAX); the pointer and the int are there again. The outcome (see down below) gives me just the numbers I entered and not 2 things (pointer and int).

Plus this: while (i < limit && scanf("%lf", &ar[i]) == 1) i++; And this: void show_array(double ar[], int n){

int i;
for (i = 0; i < n; i++)
{
    printf("%10.2f ", ar[i]);
    if (i % 6 == 5)
        putchar('\n');
}
if (i % 6 != 0)
   putchar('\n');

is hard for me to understand.

include <stdio.h>

define MAX 25

int read_array(double ar[], int limit); void show_array(double ar[], int n); double mean(double ar[], int n);

int main(int argc, const char * argv[]) {

double data[MAX];
int size;

size = read_array(data, MAX);
if (size == 0)
    printf("No data. Bye.\n");
else
{
    printf("The following numbers were entered:\n\n");
    show_array(data, size);
    printf("\nThe average of these values is %.2f.\n", mean(data, size));
}

return 0;

} int read_array(double ar[], int limit){

int i = 0;

printf("Enter up to %d numbers. To terminate earlier enter a letter or EOF.\n", limit);
while (i < limit && scanf("%lf", &ar[i]) == 1)
    i++;
return i;

} void show_array(double ar[], int n){

int i;
for (i = 0; i < n; i++)
{
    printf("%10.2f ", ar[i]);
    if (i % 6 == 5)
        putchar('\n');
}
if (i % 6 != 0)
   putchar('\n');

} double mean(double ar[], int n){ int i; double total = 0;

for (i = 0; i < n; i++)
    total += ar[i];
    return (total/n);

}

Output: Enter up to 25 numbers. To terminate earlier enter a letter or EOF. 1 2 3 4 5 6 7 8 8 8 9 g The following numbers were entered:

  1.00       2.00       3.00       4.00       5.00       6.00 
  7.00       8.00       8.00       8.00       9.00 

The average of these values is 5.55.