What is C++ - Interactive Quiz & Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print "Hello, C++!" to the console.

C++

#include <iostream>

int main() {
    std::cout << [1] << std::endl;
    return 0;
}

Drag options to blanks, or click blank then click option'

A"Hello, C++!"

BHello, C++!

Ccout << "Hello, C++!"

Dstd::endl

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the double quotes around the text.

Trying to print without std::cout.

The text to print must be a string literal enclosed in double quotes.

2fill in blank

medium

Complete the code to declare an integer variable named 'age' with value 25.

C++

int [1] = 25;

Drag options to blanks, or click blank then click option'

Avalue

Bnumber

Cage

Dint

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong variable name.

Trying to declare type twice.

Variable name should be 'age' as requested.

3fill in blank

hard

Fix the error in the code to correctly return 0 from main.

C++

int main() {
    return [1];
}

Drag options to blanks, or click blank then click option'

A0

Bone

C"0"

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a string instead of an integer.

Returning a non-zero value.

The return value must be the integer 0, not a string or other value.

4fill in blank

hard

Fill both blanks to declare a float variable 'pi' with value 3.14.

C++

[1] [2] = 3.14;

Drag options to blanks, or click blank then click option'

Afloat

Bdouble

Cpi

Dint

Attempts:

3 left

💡 Hint

Common Mistakes

Using int type for decimal values.

Wrong variable name.

Use 'float' as type and 'pi' as variable name.

5fill in blank

hard

Fill all three blanks to create a simple if statement that prints "Yes" if x is greater than 10.

C++

#include <iostream>

int main() {
    int x = 15;
    if (x [1] [2]) {
        std::cout << [3] << std::endl;
    }
    return 0;
}

Drag options to blanks, or click blank then click option'

A<

B10

C"Yes"

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operator.

Forgetting quotes around the string.

The condition is 'x > 10' and the printed text is "Yes".

Practice

1. What is C++ primarily used for?

easy

A. Managing databases only

B. Designing websites

C. Creating fast and efficient programs

D. Writing poetry

Solution

1. Step 1: Understand C++ purpose

   C++ is a programming language designed for speed and efficiency.

2. Step 2: Compare options

   Only Creating fast and efficient programs matches the main use of C++ for fast and efficient programs.

3. Final Answer:

   Creating fast and efficient programs -> Option C

4. Quick Check:

   C++ use = Creating fast and efficient programs [OK]

Hint: Remember C++ is for fast programs, not just websites [OK]

Common Mistakes:

• Confusing C++ with web design languages
• Thinking C++ is only for databases
• Assuming C++ is for creative writing

2. Which of the following is the correct way to start a C++ program?

easy

A. int main() {}

B. void start() {}

C. begin() {}

D. function main() {}

Solution

1. Step 1: Identify C++ program entry point

   C++ programs start execution from the main function.

2. Step 2: Check syntax correctness

   Only int main() {} is valid C++ syntax for program start.

3. Final Answer:

   int main() {} -> Option A

4. Quick Check:

   Program start = int main() {} [OK]

Hint: Look for int main() as the program start [OK]

Common Mistakes:

• Using void instead of int for main
• Using non-C++ keywords like function or begin
• Missing return type in main function

3. What will the following C++ code output?

int main() {
  int x = 5;
  int y = 3;
  int z = x + y;
  std::cout << z;
  return 0;
}

medium

A. 53

B. Error

C. 0

D. 8

Solution

1. Step 1: Calculate the sum of x and y

   x is 5 and y is 3, so z = 5 + 3 = 8.

2. Step 2: Understand output statement

   std::cout << z; prints the value of z, which is 8.

3. Final Answer:

   8 -> Option D

4. Quick Check:

   5 + 3 = 8 [OK]

Hint: Add numbers before output to find result [OK]

Common Mistakes:

• Concatenating numbers as strings
• Expecting syntax error due to missing headers
• Confusing variable names

4. Find the error in this C++ code:

int main() {
  int number = 10
  std::cout << number;
  return 0;
}

medium

A. Wrong variable type

B. Missing semicolon after variable declaration

C. Missing return statement

D. Incorrect output syntax

Solution

1. Step 1: Check variable declaration line

   The line int number = 10 is missing a semicolon at the end.

2. Step 2: Verify other lines

   Other lines are correct: output and return statements are fine.

3. Final Answer:

   Missing semicolon after variable declaration -> Option B

4. Quick Check:

   Semicolon missing = syntax error [OK]

Hint: Look for missing semicolons after statements [OK]

Common Mistakes:

• Ignoring missing semicolon errors
• Assuming return statement is missing
• Thinking output syntax is wrong

5. You want to write a C++ program that prints "Hello, C++!" to the screen. Which code snippet correctly does this?

hard

A. int main() { std::cout << "Hello, C++!"; return 0; }

B. void main() { print("Hello, C++!"); }

C. main() { cout << Hello, C++!; }

D. int start() { std::cout << "Hello, C++!"; }

Solution

1. Step 1: Check function signature

   Only int main() is the correct entry point for C++ programs.

2. Step 2: Verify output syntax

   std::cout << "Hello, C++!"; correctly prints the message.

3. Step 3: Confirm return statement

   Return 0 indicates successful program end.

4. Final Answer:

   int main() { std::cout << "Hello, C++!"; return 0; } -> Option A

5. Quick Check:

   Correct main and output syntax = int main() { std::cout << "Hello, C++!"; return 0; } [OK]

Hint: Use int main() and std::cout for output [OK]

Common Mistakes:

• Using void main() instead of int main()
• Missing quotes around string
• Using undefined print function