COMP1511 17s1 Introduction to Programming
The tutorial will start with a code review.

Your tutor has asked a lab pair to present their week 4 work.

Discuss the good, the bad and the ugly aspects of their code.

Please be gentle in any criticism - we are all learning!

1. New lab pairs - you have a new lab partner for weeks 5-8.
2. Did you blog last week? What is this week's blogging theme?

3. How is the game of Farnakle played?

4. Calculate the number of farnarkles and arkles for each pair of these sequences:
Hidden SequenceGuess
4 4 4 44 4 4 4
1 1 1 14 4 4 4
1 4 1 14 4 1 4
1 1 4 14 4 1 4
1 2 3 44 3 2 1
1 2 3 42 1 3 4
5 6 7 86 6 7 7
1 8 2 77 8 1 2
1 1 2 34 1 1 1
1 2 2 12 2 2 2

5. What does this code print and why:
```srand(time(NULL));
printf("%d\n", rand() % 6 + 1);
```

6. What is an array?

7. Give an expression that sums the first and third element of an array called `numbers`

8. If an array is declared as `int numbers;` and your program assigns a value to each element in the array, what is the problem with the statement `x = numbers;` ?

9. How would you declare a variable squares to be an array of integers with 15 elements?

Write a C code fragment to store, in each element of this array, the square of the index of that element, e.g., squares would contain the value 25.

10. Write a function with this prototype
```int array_length(int nums[])
```
which returns the number of elements in the array `nums`.

11. Write a function with this prototype
```int test_all_initialized(int nums[])
```
which returns 1 if all elements of array `nums` are initialized, otherwise returns 0.

12. Write a C function that searches for a given int in an array and returns 0 if the array contains the int and 1 otherwise. Your function should use the following prototype
```int not_in_int_array(int nums[], int n, int x);
```

13. Write a C function that that calculates the dot-product of two vectors of integers. Your function should use the following prototype
```int dot_product(int vector1[VECTOR_LENGTH], int vector2[VECTOR_LENGTH])
```

Reminder: you calculate the dot product by multiplying corresponding elements and summing the result.

So the dot-product of 1 3 1 3 2 and 2 1 2 1 2 is 14.

### Revision questions

The remaining tutorial questions are primarily intended for revision - either this week or later in session.

Your tutor may still choose to cover some of the questions time permitting.

14. Write a C function that returns the maximum value found in an array of doubles.

It should have this prototype:

```double max_value(double array[], int length)
```

15. Write a C function that returns 1 if an array of ints is in increasing order, 0 otherwise,

It should have this prototype:

```int increasing(double array[], int length)
```

16. Write a C program `occur.c` which reads 6 numbers then reads another number and prints how many times that number occurred in the first 5. For example:
```./occur
Enter 6 numbers: 1 3 1 3 1 9
Enter a number: 1
1 occurred 3 times in the 6 numbers read
```
Make sure you make you make it very easy to change how many numbers the program reads.

17. This C code:
```    int x;
int a;

x = 10;
a[3 * 2] = 2 * 3 * 7;
printf("%d\n", x);
```
mysteriously printed `42`. How could this happen when `x` is clearly assigned only the value `10`?

How can you easily detect such errors before they have mysterious effects?

18. Write a C program which reads numbers until end-of-input is reached and then prints the middle number.

So if 9 numbers were entered the program should print the 5th number entered. And if 27 numbers were entered the program should print the 14th number entered.

If an even number of numbers is entered there are two middle numbers, print the second of them.

For example if 8 numbers are entered, prints the 5th.

You can assume at most 10,000 numbers will be entered.

19. Write a C function that takes in an array of integers, and returns the average.
```        double average(int numbers[], int num_elements);
```

20. Write a C function that takes in an array of integers, and returns the difference between the smallest and largest numbers in it.
```        double maxDifference(int numbers[], int num_elements);
```