Why the output is coming as zero?

Question

#include <iostream>
using namespace std;

int main() {
int const N= 5;
int arr[N]={1,7};
int prod=1;
for(int i=0;i<5;i++){
prod*=arr[i];

}
cout<<prod;
return 0;
}

Answer 1

I had a mistake in my answer.
If you initialization an array this way all under values get set to 0.
int arr[5] = {1, 7}
-> 1 7 0 0 0

int arr[5];
-> 5x garbage value.

So the answer to you question:
prod = 1 * 1 * 7 * 0 * 0 * 0
The first 1 is the initial value.

Answer 2

https://code.sololearn.com/c9YLtBe1nkkD/?ref=app

Answer 3

Here are your mistakes:
1st: Array indexes start with 0. You loop starts with 1. You need to change int i=1 to int i=0
[forget #2. It's wrong. See my other answer]
[2nd: You just assign 2 values to the array and then put the unassigned values into your calculation. You should never use unassigned values.
In this case there are 3 garbage values and one of them is a zero.]

You can easily debug such a code with putting a
cout << arr[i] << endl
inside the for loop. That would've made the mistakes clearer.

Answer 4

but it's a challenge round ques and there we can't change the code and check, so is this code wrong acc to you?
PS. 'i' has initial value 0 only, I by mistake made it 1 .

Answer 5

Oh okay ,but dis is working in C++ only ,as I have written parallel code for C and then it's giving me garbage value for unassigned values of an array

Answer 6

thanks a lot 😊