Set pointer to int value in loop

Question

I have been skimming around the website trying to find answer to my question, but I can't seem to find it. I was wondering why I am getting an strange number when trying to increase my pointer to int value.

At first I thought it might be because I didn't enclose my variable *sum with braces, but it does not help either.

I dont really see why I am unable to continuously increase sum pointer :@. I am assuming I am changing the address of sum instead of the value, but I am not sure why.

int userNumber;
int * sum = new int;
while (std::cin >> userNumber)
{
    if (userNumber == 0)
        break;
    else
        (*sum) += userNumber;
}
std::cout << "Loop ended with value: " << *sum << std::endl;

Any help would be lovely!

Why not print the value at the beginning of the loop?

juanchopanza
– juanchopanza

2018-01-21 20:42:38 +00:00
Commented Jan 21, 2018 at 20:42 — juanchopanza
– juanchopanza, Commented Jan 21, 2018 at 20:42
You can jump straight into the question

Gibolt
– Gibolt

2018-01-21 21:04:51 +00:00
Commented Jan 21, 2018 at 21:04 — Gibolt
– Gibolt, Commented Jan 21, 2018 at 21:04

Some programmer dude · Accepted Answer · 2018-01-21 20:45:34Z

3

When you allocate the int with new int, it is not initialized. Its value will be indeterminate and using it in any way without initialization will lead to undefined behavior.

You need to initialize it, which you can do with the allocation:

int * sum = new int(0);

answered Jan 21, 2018 at 20:45

Some programmer dude

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