Question 3: Explaining pointers

Here is some C++ code. It uses a single function, which takes a square matrix of non-negative integers as

an input and processes it. This question asks you to explain, in detail, what the code does.

#include

using namespace std;

const int n = 3;

int* all(int v[n][n]) { // Assumption: v contains non-negative integers

int m = 0;

int *ret = NULL;

for (int i=0; i < n; i++)

for (int j=0; j < n; j++)

if (v[i][j] > m) {

m = v[i][j];

ret = &(v[i][j]);

}

return ret;

}

int main() {

int t[n][n] = {{1, 23, 1}, {4, 0, 6}, {0, 12, 3}}; // Every element >= 0

int *p = all(t);

while (p != NULL) {

cout << *p << endl;

*p = 0;

p = all(t);

}

return 0;

}

Specifically, in your explanation address the following aspects:

1. What does all() do? If you were to give it a better name, what might that be? Pointers are usedwhy are they used?

2. What does the code output? (There is a description with one or two simple sentences.) Answer this first with respect to the given input, but then generalize to explain what it does for other matrices t.

(For guidance, work out how many lines are printed. It this always the same number, or does it depend on particular properties of the matrix?)

3. What variables, if any, undergo important state changes?