Chapter 1 Beginner 55 Questions

Practice Questions — Introduction to C++

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12 Easy

11 Medium

9 Hard

Topic-Specific Questions

Question 1

Easy

What is the output of the following code?

#include <iostream>
using namespace std;
int main() {
    cout << "Hello, World!";
    return 0;
}

cout << sends text to the standard output.

Hello, World!

Question 2

Easy

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << sizeof(char) << endl;
    return 0;
}

The size of char is defined by the C++ standard.

1

Question 3

Easy

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << sizeof(int) << endl;
    return 0;
}

On most modern 64-bit systems, int is 4 bytes.

4

Question 4

Easy

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << "Line 1" << endl;
    cout << "Line 2" << endl;
    return 0;
}

endl inserts a newline and flushes the buffer.

Line 1
Line 2

Question 5

Easy

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << 10 + 20 << endl;
    return 0;
}

The expression is evaluated first, then the result is printed.

30

Question 6

Medium

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << "Value: " << 5 << " + " << 3 << " = " << 5 + 3 << endl;
    return 0;
}

The << operator chains multiple outputs. Expressions are evaluated when reached.

Value: 5 + 3 = 8

Question 7

Medium

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << sizeof(double) << endl;
    cout << sizeof(long long) << endl;
    return 0;
}

double and long long are both 8 bytes on most modern systems.

8
8

Question 8

Easy

Who created C++ and when? What was it originally called?

Think Bell Labs, late 1970s.

C++ was created by Bjarne Stroustrup in 1979 at Bell Labs. It was originally called "C with Classes" and renamed to C++ in 1983.

Question 9

Easy

Name any four real-world applications or domains where C++ is heavily used.

Think about software that needs to be very fast.

C++ is heavily used in: (1) Game engines (Unreal Engine), (2) Operating systems (Windows, parts of Linux), (3) Web browsers (Chrome, Firefox), and (4) Competitive programming (Codeforces, ICPC). Other domains include databases (MySQL), finance (HFT), and embedded systems.

Question 10

Medium

Explain the four stages of the C++ compilation process.

Source code goes through four transformations before becoming an executable.

The four stages are: (1) Preprocessing -- expands #include directives, macros, and conditional compilation. (2) Compilation -- converts preprocessed source to assembly language. (3) Assembly -- converts assembly to machine code (object file, .o). (4) Linking -- combines object files and library references into the final executable.

Question 11

Medium

What are three key differences between C++ and Java?

Think about memory management, compilation, and language features.

(1) Memory management: C++ uses manual memory management (new/delete, smart pointers) while Java has automatic garbage collection. (2) Compilation: C++ compiles to native machine code, while Java compiles to bytecode that runs on the JVM. (3) Multiple inheritance: C++ supports multiple inheritance of classes, while Java only allows multiple interface implementation.

Question 12

Medium

What was the significance of C++11? Name at least four features it introduced.

C++11 was called 'Modern C++' because of how many features it added.

C++11 was the biggest update to C++ since its original standardization. Key features: (1) auto keyword for type inference, (2) Range-based for loops, (3) Lambda expressions, (4) Smart pointers (unique_ptr, shared_ptr), (5) Move semantics and rvalue references, (6) nullptr replacing NULL, (7) constexpr for compile-time computation, (8) Threading support.

Question 13

Medium

What happens when you compile and run this code?

#include <iostream>
int main() {
    std::cout << "No using namespace" << std::endl;
    return 0;
}

Without 'using namespace std', you must prefix std:: before cout and endl.

It compiles and runs successfully. Output: No using namespace

Question 14

Hard

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << sizeof(sizeof(int)) << endl;
    return 0;
}

sizeof returns a value of type size_t. What is the size of size_t?

8 (on a 64-bit system) or 4 (on a 32-bit system)

Question 15

Hard

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << "Hello";
    cout << " World";
    cout << endl;
    return 0;
}

Multiple cout statements without endl do not insert newlines between them.

Hello World

Question 16

Hard

What is the difference between a compiler error and a linker error in C++? Give an example of each.

Compiler errors happen during the compilation stage. Linker errors happen when combining object files.

A compiler error occurs when the source code has syntax errors or type mismatches. Example: using a variable without declaring it (x = 5; without int x;). A linker error occurs when the compiler succeeds but the linker cannot find a function or variable definition. Example: declaring void myFunc(); and calling it, but never providing the function body -- the linker cannot resolve the reference.

Question 17

Hard

Why is C++ preferred over Python in competitive programming despite Python being easier to write?

Think about execution speed and time limits.

C++ is preferred in competitive programming for three reasons: (1) Speed: C++ is 10-100x faster than Python, and CP problems have strict time limits (usually 1-2 seconds). A solution that passes in C++ may get TLE (Time Limit Exceeded) in Python. (2) STL: The Standard Template Library provides optimized data structures (set, map, priority_queue) and algorithms (sort, lower_bound) out of the box. (3) Deterministic performance: No garbage collector pauses or interpreter overhead.

Question 18

Easy

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << "C" << "+" << "+" << endl;
    return 0;
}

Each << outputs its operand sequentially.

C++

Question 19

Medium

What does the preprocessor directive #include do? What is the difference between #include and #include "myfile.h"?

Think about where the compiler looks for the file.

#include tells the preprocessor to copy the entire contents of the specified file into the current file before compilation. #include <iostream> (angle brackets) searches in the system/standard library directories. #include "myfile.h" (double quotes) searches in the current directory first, then falls back to system directories.

Question 20

Hard

Does this program compile? If yes, what is the output?

#include <iostream>
using namespace std;
int main() {
    cout << sizeof('A') << endl;
    return 0;
}

In C, sizeof('A') is 4 because character literals are ints in C. What about C++?

1

Mixed & Application Questions

Question 1

Easy

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << 100 << endl;
    cout << 200 << endl;
    return 0;
}

Each cout with endl prints on a new line.

100
200

Question 2

Easy

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << 3 + 4 * 2 << endl;
    return 0;
}

C++ follows standard mathematical operator precedence.

11

Question 3

Easy

Write a C++ program that prints your name, age, and college on three separate lines using three separate cout statements.

Use endl or '\n' after each cout to move to the next line.

#include <iostream>
using namespace std;
int main() {
    cout << "Arjun" << endl;
    cout << 20 << endl;
    cout << "IIT Delhi" << endl;
    return 0;
}

Output: Arjun 20 IIT Delhi

Question 4

Medium

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << "A" << "B" << endl << "C" << "D" << endl;
    return 0;
}

endl can appear in the middle of a chain, not just at the end.

AB
CD

Question 5

Medium

What is the difference between endl and '\n' in C++?

Both produce a newline, but one does something extra.

Both endl and '\n' insert a newline character. However, endl also flushes the output buffer, forcing all buffered output to be written to the screen immediately. '\n' just adds a newline without flushing. In competitive programming, using '\n' is faster because flushing the buffer takes time.

Question 6

Medium

What is the output?

#include <iostream>
using namespace std;
int main() {
    int a = 10;
    cout << "a = " << a << endl;
    a = 20;
    cout << "a = " << a << endl;
    return 0;
}

The variable is reassigned between the two print statements.

a = 10
a = 20

Question 7

Hard

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << sizeof(bool) << endl;
    cout << sizeof(short) << endl;
    cout << sizeof(float) << endl;
    return 0;
}

bool is 1 byte, short is 2 bytes, float is 4 bytes on most systems.

1
2
4

Question 8

Medium

Write a C++ program that declares two integer variables, assigns them values 15 and 27, and prints their sum, difference, product, and quotient.

Remember that integer division truncates the decimal part.

#include <iostream>
using namespace std;
int main() {
    int a = 15, b = 27;
    cout << "Sum: " << a + b << endl;
    cout << "Difference: " << a - b << endl;
    cout << "Product: " << a * b << endl;
    cout << "Quotient: " << a / b << endl;
    return 0;
}

Output: Sum: 42 Difference: -12 Product: 405 Quotient: 0

Question 9

Hard

Does this code compile? If yes, what is the output?

#include <iostream>
using namespace std;
int main() {
    cout << "Size: " << sizeof("Hello") << endl;
    return 0;
}

String literals in C++ are arrays of char, and they have a null terminator.

Size: 6

Question 10

Hard

Explain what 'using namespace std;' does and why some programmers avoid it in large projects.

Think about what happens when two libraries define a function with the same name.

The using namespace std; directive imports all names from the std namespace into the current scope. This lets you write cout instead of std::cout. In large projects, this is avoided because it can cause name collisions -- if you define your own function called count or distance, it conflicts with std::count or std::distance from the standard library, leading to ambiguous calls.

Question 11

Easy

What is the output?

#include <iostream>
using namespace std;
int main() {
    cout << "Hello " << 2026 << "!" << endl;
    return 0;
}

You can chain strings and numbers together with <<.

Hello 2026!

Question 12

Hard

What is the output?

#include <iostream>
using namespace std;
int main() {
    int x = 5;
    cout << sizeof(x) << " " << sizeof(x + 1.0) << endl;
    return 0;
}

When int and double are added, the result is promoted to double.

4 8

Multiple Choice Questions

MCQ 1

Who created C++?

A. Dennis Ritchie
B. Bjarne Stroustrup
C. James Gosling
D. Guido van Rossum

Answer: B
B is correct. Bjarne Stroustrup created C++ in 1979 at Bell Labs. Dennis Ritchie (A) created C. James Gosling (C) created Java. Guido van Rossum (D) created Python.

MCQ 2

What was C++ originally called?

A. C Plus
B. Advanced C
C. C with Classes
D. New C

Answer: C
C is correct. Stroustrup originally named the language 'C with Classes' because his goal was to add class-based object-oriented programming to C. It was renamed to C++ in 1983.

MCQ 3

What does the ++ in C++ represent?

A. Plus plus, meaning additional features
B. The increment operator from C, meaning one step beyond C
C. Two plus signs for double the power
D. It is just a brand name with no meaning

Answer: B
B is correct. In C, the ++ operator increments a value by 1. So C++ literally means 'C incremented by 1' -- one step beyond C. This clever naming reflects that C++ is an evolution of C.

MCQ 4

Which of the following is NOT a feature of C++?

A. Object-oriented programming
B. Automatic garbage collection
C. Low-level memory access via pointers
D. Compiled to native machine code

Answer: B
B is correct. C++ does NOT have automatic garbage collection like Java or Python. In C++, the programmer is responsible for managing memory using new and delete (or smart pointers in modern C++). All other options are genuine C++ features.

MCQ 5

Which header file is needed to use cout and cin?

A. <stdio.h>
B. <conio.h>
C. <iostream>
D. <string>

Answer: C
C is correct. <iostream> provides cout, cin, cerr, clog, and endl. <stdio.h> (A) is the C header for printf/scanf. <conio.h> (B) is a non-standard header. <string> (D) is for the string class.

MCQ 6

What is the correct return type of the main() function in standard C++?

A. void
B. int
C. float
D. double

Answer: B
B is correct. The C++ standard requires main() to return int. return 0; indicates successful execution. While some older compilers accept void main(), it is not standard-compliant and should be avoided.

MCQ 7

What is the output of sizeof(char) in C++?

A. 0
B. 1
C. 2
D. Depends on the platform

Answer: B
B is correct. The C++ standard guarantees that sizeof(char) is always 1 byte on every platform and every compiler. This is the only type with a guaranteed fixed size.

MCQ 8

Which of the following is the correct compilation command for a C++ file using g++?

A. gcc file.cpp -o output
B. g++ file.cpp -o output
C. cpp file.cpp -o output
D. compile file.cpp -o output

Answer: B
B is correct. g++ is the GNU C++ compiler. The -o output flag specifies the name of the output executable. While gcc (A) can compile C++ with the -lstdc++ flag, g++ is the standard approach. cpp (C) is the preprocessor, not the compiler.

MCQ 9

Which stage of the C++ compilation process resolves #include directives?

A. Compilation
B. Assembly
C. Preprocessing
D. Linking

Answer: C
C is correct. The preprocessor runs before the compiler and handles all directives starting with #: #include, #define, #ifdef, etc. It replaces #include <iostream> with the actual file contents.

MCQ 10

What does 'return 0;' in main() signify?

A. The program output is 0
B. The program has zero variables
C. The program terminated successfully
D. The program runs zero more times

Answer: C
C is correct. return 0; sends an exit code of 0 to the operating system, which conventionally means the program executed successfully. A non-zero return value (like 1) indicates an error.

MCQ 11

In C++, sizeof('A') evaluates to what value?

A. 1
B. 2
C. 4
D. 8

Answer: A
A is correct. In C++, character literals like 'A' have type char, which is 1 byte. This is different from C, where 'A' has type int (4 bytes). This difference is a classic C/C++ interview question.

MCQ 12

Which C++ standard introduced smart pointers, lambda expressions, and the auto keyword?

A. C++98
B. C++03
C. C++11
D. C++17

Answer: C
C is correct. C++11 was the landmark update that introduced auto, lambda expressions, smart pointers (unique_ptr, shared_ptr), range-based for loops, move semantics, nullptr, and much more. It is often called 'Modern C++.'

MCQ 13

What is the output of sizeof("Hi") in C++?

A. 2
B. 3
C. 4
D. 8

Answer: B
B is correct. The string literal "Hi" is stored as a char array {'H', 'i', '\0'}. The null terminator adds 1 extra byte. So sizeof("Hi") = 2 characters + 1 null terminator = 3 bytes.

MCQ 14

Which of the following is NOT a valid C++ file extension?

A. .cpp
B. .cc
C. .cxx
D. .c++

Answer: D
D is correct. While .cpp, .cc, and .cxx are all valid and commonly recognized C++ file extensions, .c++ is problematic because the + character is not universally supported in filenames across all operating systems and build tools.

MCQ 15

What does the linker do in the C++ compilation process?

A. Converts source code to assembly language
B. Expands #include and #define directives
C. Converts assembly to machine code
D. Combines object files and resolves external references to produce the executable

Answer: D
D is correct. The linker takes one or more object files (.o files), resolves references between them (e.g., function calls across files), links in the standard library, and produces the final executable. Option A is the compiler, B is the preprocessor, C is the assembler.

MCQ 16

Which of the following is true about C++ compared to Java?

A. C++ runs on a virtual machine like Java's JVM
B. C++ has automatic garbage collection
C. C++ supports multiple inheritance of classes
D. C++ does not support operator overloading

Answer: C
C is correct. C++ supports multiple inheritance (a class can inherit from multiple base classes), while Java only supports single class inheritance (multiple interface implementation is allowed). C++ compiles to native code, not a VM (A is wrong). C++ has no GC (B is wrong). C++ fully supports operator overloading (D is wrong).

MCQ 17

Which operator is used for output in C++?

A. >>
B. <<
C. ->
D. ::

Answer: B
B is correct. The << operator (insertion operator) is used with cout for output. The >> operator (extraction operator) is used with cin for input. -> is for accessing members via pointers. :: is the scope resolution operator.

MCQ 18

What is the value of __cplusplus macro when compiling with C++17 standard?

A. 201103L
B. 201402L
C. 201703L
D. 202002L

Answer: C
C is correct. The __cplusplus macro is set to 201703L for C++17. The values correspond to the year and month of the standard's publication: 201103L (C++11), 201402L (C++14), 201703L (C++17), 202002L (C++20).

MCQ 19

Which of these correctly describes C++?

A. Interpreted, dynamically typed
B. Compiled, dynamically typed
C. Interpreted, statically typed
D. Compiled, statically typed

Answer: D
D is correct. C++ is a compiled language (source code is compiled to native machine code) and statically typed (variable types are determined at compile time and cannot change). Python is interpreted and dynamically typed. JavaScript is interpreted and dynamically typed.

MCQ 20

Which C++ feature is used to write generic, type-independent code?

A. Inheritance
B. Polymorphism
C. Templates
D. Encapsulation

Use only cout and string literals. No loops.

#include <iostream>
using namespace std;
int main() {
    cout << "  *" << endl;
    cout << " ***" << endl;
    cout << "*****" << endl;
    cout << " ***" << endl;
    cout << "  *" << endl;
    return 0;
}

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