Array initialization in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of partially initialized array

What is the output of this C++ code snippet?

C++

#include <iostream>
int main() {
    int arr[5] = {1, 2};
    for(int i = 0; i < 5; ++i) {
        std::cout << arr[i] << " ";
    }
    return 0;
}

A 1 2 0 1 2

B 1 2 3 4 5

C 1 2 0 0 1

D 1 2 0 0 0

💡 Hint

Uninitialized elements in an array initialized with fewer values are set to zero.

In C++, when an array is partially initialized, the remaining elements are zero-initialized automatically.

❓ Predict Output

intermediate

Output of array initialization with all zeros

What will be the output of this C++ code?

C++

#include <iostream>
int main() {
    int arr[4] = {};
    for(int i = 0; i < 4; ++i) {
        std::cout << arr[i] << " ";
    }
    return 0;
}

A 0 0 0 0

B Garbage values

C 1 1 1 1

D Compilation error

💡 Hint

Empty braces initialize all elements to zero.

Using empty braces {} initializes all elements of the array to zero in C++.

❓ Predict Output

advanced

Output of array initialization with string literals

What is the output of this C++ code snippet?

C++

#include <iostream>
int main() {
    const char* arr[3] = {"apple", "banana", "cherry"};
    std::cout << arr[1] << std::endl;
    return 0;
}

A Compilation error

B banana

C apple

D cherry

💡 Hint

Array holds pointers to string literals; arr[1] is the second element.

The array stores pointers to string literals. arr[1] points to "banana".

❓ Predict Output

advanced

Output of multidimensional array initialization

What is the output of this C++ code?

C++

#include <iostream>
int main() {
    int arr[2][3] = {{1, 2}, {3}};
    for(int i = 0; i < 2; ++i) {
        for(int j = 0; j < 3; ++j) {
            std::cout << arr[i][j] << " ";
        }
    }
    return 0;
}

A 1 2 0 3 0 1

B 1 2 3 3 0 0

C 1 2 0 3 0 0

D 1 2 0 3 1 0

💡 Hint

Uninitialized elements in nested arrays are zero.

In multidimensional arrays, missing elements in inner braces are zero-initialized.

🧠 Conceptual

expert

Behavior of static array initialization inside a function

Consider this C++ code. What will be the output after the function is called twice?

C++

#include <iostream>
void func() {
    static int arr[3] = {5};
    for(int i = 0; i < 3; ++i) {
        std::cout << arr[i] << " ";
        arr[i] += 1;
    }
    std::cout << std::endl;
}
int main() {
    func();
    func();
    return 0;
}

A

5 0 0 
6 1 1 

B

5 0 0 
5 0 0 

C

5 0 0 
6 0 0 

D

5 0 0 
6 1 0 

💡 Hint

Static arrays keep their values between function calls.

Static arrays are initialized once. On first call, arr is {5,0,0}. After increment, arr becomes {6,1,1}. On second call, updated values print.