Trying to debug and correct a function - c++

Question

#include <iostream>
#include <string>
using namespace std;
// Declaration of the function indexvalue()
int *maxArr(int [], const int);
// Another function used to print out an error message
void
problem(string str) {
cout << str << endl;
exit(1);
}
const int Size = 10;
int main()
{
int a[Size] = {23, 45, 12, 76, 9, 131, 10, 8, 23, 4};
int *b, i;
string error1("Problem with maxArr(), wrong subscript");
string error2("Problem with maxArr(), output should be NULL");
// Call the function multiple times with different input
// Note the use of pointer arithmetic
if (maxArr(a,Size)!= a+5) problem(error1);
if (maxArr(a,Size-5)!= a+3) problem(error1);
if (maxArr(a+6,4)!= a+8) problem(error1);
if (maxArr(a,0)!= NULL) problem(error2);
// The function passed all the tests
cout << "The function passed all the tests in this program\n" << endl;
exit(0);
}
int *maxArr(int arr[], int size){
int max = 0;
int index = 0;
if ( size < 0)
return NULL;
for (int i = 0; i < size; i++) {
if (arr[i] > max )
{
max = arr[i];
index = i;
}
return arr + i;
}
}
Specifications for maxArr()
The function accepts an integer array, and the number of elements as parameters.
The function returns the address of an int which points at the maximum value of the array.
i'm trying to figure out what's wrong with the maxArr() function and the only thing i've corrected so far is changing if(size < 0) to if (size <= 0) to handle the null case, I have no idea how to correct the function to account for the error1 message. Any help would be appreciated.

Answer 1

You have a brackets issue here:
for (int i = 0; i < size; i++) {
if (arr[i] > max )
{
max = arr[i];
index = i;
}
return arr + i;
}
Your return is within the for loop and therefore you will return on the first interation of the loop.
index is not used, you probably want to move the return statement outside the main loop and return arr + index;

Answer 2

You are returning from inside the for loop in the function maxArr. It will always return in the first iteration. Also you should return arr+index instead of arr+i.
for (int i = 0; i < size; i++)
{
if (arr[i] > max )
{
max = arr[i];
index = i;
}
//return arr + i;
// ^^^^ Wrong
}
return arr+index; //return from here
The check for returning NULL will fail with your current condition. You should check like this:
if ( size <= 0)
return NULL;