SI204: Pointers & Arrays II [HW]

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[12pts] Suppose we want to read an array size from user, but worry about the user entering 0 or a negative num.


int n;
cin >> n;
double *Z;
Z = new double[n];
if( n <= 0 ) {
  cout << "Error!" << endl;
  Z = new double[10];
}

Z[0] = 5;


int n;
cin >> n;
if( n <= 0 ) {
  cout << "Error!" << endl;
  double *Z = new double[10];
}
else
  double *Z = new double[n];

Z[0] = 5;


int n;
cin >> n;
double *Z;
if( n <= 0 ) {
  cout << "Error!" << endl;
  Z = new double[10];
}
else
  Z = new double[n];

Z[0] = 5;

compile-time error / possible run-time error / OK
If error, why? compile-time error / possible run-time error / OK
If error, why? compile-time error / possible run-time error / OK
If error, why?

[88pts] Write a program that reads n points from standard input in the following format
```
N = n
(x1,y1) (x2,y2) ... (xn,yn)
```
and writes out the x-coordinates of all n points on one line, and the y-coordinates of all n points on the following line. The output must be formatted like this:
```
X := [x1, x2, ..., xn]
Y := [y1, y2, ..., yn]
```
Here are some example runs. Your program must read input and produce output with the exact same formatting!
```
~/$ ./hw
N = 4
(0.5,1) (0.6,1.5) (0.7,2) (0.8,2.5)
X := [0.5, 0.6, 0.7, 0.8]
Y := [1, 1.5, 2, 2.5]
~/$./hw
N = 1
(5,8)
X := [5]
Y := [8]
~/$./hw
N = 10
(11,51) (12,52) (13,53) (14,54) (15,55) (16,56) (17,57) (18,58) (19,59) (20,60)
X := [11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
Y := [51, 52, 53, 54, 55, 56, 57, 58, 59, 60]
```
Note: You may assume there is at least one point, i.e. you never get input like N = 0.
Turn In your source code and a screen capture of your program running on above example. (Hint: This is most easily done with two arrays.)