Question

I’m expecting the code below to print 1 but its printing a random large number.
I don’t understand why this is happening, please advise.

#include <iostream>
using namespace std;

int * returnArray()
{
    int myArray[5]={1,2,3,4,5};
    return myArray;
}

void printArray(int * myArray)
{
    cout << *myArray<< endl;
}

int main()
{
    printArray(returnArray());
}

Answer 1

In your code, returnArray returns a pointer to the first element of myArray, which is local to the function. When the function returns, the memory of its local variables gets released as the call stack is popped, so it can be used for other purposes. In this case, since you call printArray afterwards, the stack area originally occupied by returnArray gets reused for printArray, so the memory that originally contained myArray now has unpredictable content.

As James Kanze pointed out, the best way to accomplish what you want would probably be to use std::vector<int> instead of int*, something like this

std::vector<int> returnArray()
{
    int myArray[5] = { 1, 2, 3, 4, 5 };
    std::vector<int> result(myArray, myArray + 5);
    return result
}

And modify the other functions accordingly to take a vector. Note that in printArray you need myVector[0] to access the first element, as vectors aren’t pointers.