Week 05 Tutorial Questions

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!

New lab pairs - you have a new lab partner for weeks 5-7.
Write a function with this prototype
```
int array_length(int nums[])
```
which returns the number of elements in the array nums.
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.
Write a function that takes in a 2d array of ints and multiplies every value in the array by a given int.
It will have this prototype:
```
void scalar_multiply(int rows, int columns, int matrix[rows][columns],  int scalar)
```
What will happen when each of the following statements is executed (in order)?
```
int n = 42;
int *p, *q;
p = &n;
*p = 5;
*q = 17;
q = p;
*q = 8;
```
Filling out the follwing table may be helpful:

Address int n = 42; int *p;
int *q; p = &n; *p = 5; *q = 17; q = p; *q = 8;

0xFF80

0xFF84

0xFF88

0xFF8C

0xFF90

Note: Address lengths have been reduced for brevity.
This C code:
```
int x;
int a[6];

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 does the output change if we create a another int after the array?
How can you easily detect such errors before they have mysterious effects?
Write a void function which places the sum of two numbers inside a variable passed in by reference. It should have the following prototype:
```
    void sum_nums(int a, int b, int *sum);
```