| 5.12. Activities | ||
|---|---|---|
 | Chapter 5. Pointers in C |  |
| 5.12. Activities | ||
|---|---|---|
| | Chapter 5. Pointers in C | |
Suppose that you have the following array declaration:
int table[] = {10, 20, 30, 40, 50};If you printed table[0], you would see
10. But what if you were to print *table? Would
it print anything? If so, what? If you thought an error message would print
because table is not a pointer but an array, you would be
wrong; an array name is a pointer. If you print *table, you
also would see 10.
You can make a pointer that refers to the first element of an array by simply assigning the array name to the pointer variable. If an array is referenced by a pointer, the elements in the array can be accessed with the help of the pointer:
#define SIZE 10 char *ptr_char; char chars[SIZE]; ptr_char = chars;
The name of the array, by itself, is a shorthand way of
saying ptr_char = &chars[0]; they mean the same thing.
You can increment or decrement a pointer. If you increment
a pointer, the address inside the pointer variable increments. The pointer
does not always increment by 1, however. It increments as the size of the
data type it refers to. This way, chars[2] and *(ptr_char +
2) are equivalent.
Having this in mind, you will calculate the average between
every pair of integers of two arrays. You will have to print the integers of
the arrays and calculate and print that average. Create a file with name
arrays_as_pointers.c in your development environment and
implement the following functionality (you may notice that it is the
same program as the one of basic arrays; however, now you have to pass
the array as a pointer):
A function that prints out the integer values of an
array: void print_array(int *array);
A second function that calculates the average between
the two elements in a same position of two arrays and prints that
average value: void calculate_average(int *array1, int
*array2);. For the first position in every array, sum the two
integers and divide the result by two, prints the result out and makes
the same for the rest of positions in the arrays.
A main function that declares and
initializes the two arrays with 10 integers (whatever you want), such as
int array1[] = {1,5,7,3,12,...};, and that makes use of the
first and second function to both print the values of the arrays and
print out the averages.
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| 5.11. Pointer Exercises |  | 5.12.2. Managing cells in your mobile phone |