Defining structures in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of structure member access

What is the output of this C++ code?

C++

struct Point {
    int x;
    int y;
};

int main() {
    Point p = {3, 4};
    std::cout << p.x + p.y << std::endl;
    return 0;
}

A 7

B 34

C 0

D Compilation error

💡 Hint

Add the values of x and y members of the structure.

The structure Point has members x=3 and y=4. Adding them gives 7.

❓ Predict Output

intermediate

Size of structure with padding

What is the size of this structure on a typical 64-bit system?

C++

struct Data {
    char a;
    int b;
    char c;
};

int main() {
    std::cout << sizeof(Data) << std::endl;
    return 0;
}

A 8

B 6

C 12

D 16

💡 Hint

Consider padding added for alignment between members.

The compiler adds padding to align int on 4 bytes. The total size becomes 12 bytes.

🔧 Debug

advanced

Identify the error in structure initialization

What error will this code produce?

C++

#include <iostream>
#include <string>

struct Person {
    std::string name;
    int age;
};

int main() {
    Person p = {"Alice"};
    std::cout << p.name << " " << p.age << std::endl;
    return 0;
}

A Compilation error: missing initializer for 'age'

B Runtime error: uninitialized age

C Output: Alice 0

D Output: Alice garbage_value

💡 Hint

All members must be initialized or have default values.

The code misses initializing 'age', causing a compilation error in strict initialization.

🧠 Conceptual

advanced

Effect of 'typedef' with structures

What does the following code do?

C++

#include <iostream>

typedef struct {
    int id;
    float score;
} Record;

int main() {
    Record r = {101, 95.5};
    std::cout << r.id << " " << r.score << std::endl;
    return 0;
}

A Defines a structure named 'Record' and a variable of that type

B Defines a structure and creates an alias 'Record' for it

C Causes a syntax error due to missing structure name

D Defines a class named 'Record' instead of a structure

💡 Hint

typedef creates a new name for the unnamed structure.

The typedef creates an alias 'Record' for the unnamed struct, allowing easy use.

❓ Predict Output

expert

Output of nested structure member access

What is the output of this code?

C++

struct Engine {
    int horsepower;
};

struct Car {
    Engine engine;
    int year;
};

int main() {
    Car c = {{250}, 2020};
    std::cout << c.engine.horsepower << " " << c.year << std::endl;
    return 0;
}

A 250 0

B Compilation error

C 0 2020

D 250 2020

💡 Hint

Nested structures can be initialized with nested braces.

The nested structure Engine is initialized with 250 horsepower, and year is 2020.