Compilation and execution process in C++ - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

C++

#include <iostream>

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

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

A"Hello, World!"

BHello, World!

Ccout << "Hello, World!"

Dstd::endl

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the double quotes around the text.

Using std::endl as the text to print.

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 'count' and initialize it to 10.

C++

int [1] = 10;

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

Avalue

Bcount

Cnumber

Dtotal

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different variable name than 'count'.

Missing the semicolon at the end.

The variable name must be 'count' as requested.

3fill in blank

hard

Fix the error in the code to correctly compile and run.

C++

#include <iostream>

int main() {
    int sum = 10;
    std::cout << "Sum is: " << [1] << std::endl;
    return 0;
}

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

Asum()

Bsum;

Csum

D"sum"

Attempts:

3 left

💡 Hint

Common Mistakes

Adding a semicolon inside the std::cout expression.

Using sum() as if it were a function.

The variable 'sum' should be used without a semicolon inside the output statement, and the statement must end with a semicolon after std::endl.

4fill in blank

hard

Fill both blanks to create a for loop that prints numbers from 1 to 5.

C++

for (int [1] = 1; [2] <= 5; ++[1]) {
    std::cout << [1] << std::endl;
}

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

Ai

Bj

Ccount

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in initialization and condition.

Forgetting to increment the loop variable.

The loop variable must be the same in initialization and condition to work correctly.

5fill in blank

hard

Fill all three blanks to declare a function named 'add' that takes two integers and returns their sum.

C++

int [1](int [2], int [3]) {
    return a + b;
}

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

Aadd

Ba

Cb

Dsum

Attempts:

3 left

💡 Hint

Common Mistakes

Using parameter names different from 'a' and 'b'.

Naming the function something other than 'add'.

The function name is 'add', and the parameters are 'a' and 'b' to match the return statement.

Practice

1. What is the main purpose of the compilation step in C++ programming?

easy

A. To convert human-readable code into machine code

B. To run the program and show output

C. To write the source code

D. To debug the program automatically

Solution

1. Step 1: Understand what compilation means

   Compilation changes the C++ source code into machine code that the computer can understand.

2. Step 2: Differentiate compilation from execution

   Execution runs the compiled machine code, but compilation itself only converts code.

3. Final Answer:

   To convert human-readable code into machine code -> Option A

4. Quick Check:

   Compilation = convert code [OK]

Hint: Compilation means converting code, not running it [OK]

Common Mistakes:

• Confusing compilation with execution
• Thinking compilation runs the program
• Believing compilation writes code

2. Which of the following is the correct command to compile a C++ file named main.cpp using g++?

easy

A. compile main.cpp

B. run main.cpp

C. g++ main.cpp -o main

D. execute main.cpp

Solution

1. Step 1: Recall the g++ compile command syntax

   The g++ compiler uses the command g++ filename.cpp -o outputname to compile.

2. Step 2: Match the command to the options

   g++ main.cpp -o main matches the correct syntax to compile main.cpp into an executable named main.

3. Final Answer:

   g++ main.cpp -o main -> Option C

4. Quick Check:

   g++ compile command = g++ main.cpp -o main [OK]

Hint: Use g++ filename.cpp -o outputname to compile [OK]

Common Mistakes:

• Using 'run' or 'execute' instead of g++
• Omitting the -o option
• Confusing compile and execute commands

3. Consider this C++ program:

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

What will happen if you try to execute this program without compiling it first?

medium

A. The program will print "Hello"

B. You will get an error saying the program is not found

C. The program will compile automatically and then run

D. The program will run but show no output

Solution

1. Step 1: Understand execution requires compiled program

   Execution runs the compiled machine code. Without compiling, no executable exists.

2. Step 2: Predict what happens if you run without compiling

   Trying to run without compiling causes an error because the executable file is missing.

3. Final Answer:

   You will get an error saying the program is not found -> Option B

4. Quick Check:

   Execution needs compiled file = error if missing [OK]

Hint: You must compile before running, or get error [OK]

Common Mistakes:

• Assuming execution auto-compiles
• Expecting output without compiling
• Thinking program runs but shows no output

4. You wrote this code in test.cpp:

#include <iostream>
int main() {
  std::cout << "Hi" << std::endl
  return 0;
}

When compiling, you get an error. What is the problem?

medium

A. Wrong return type for main

B. Missing #include <string>

C. Using std::cout incorrectly

D. Missing semicolon after std::endl

Solution

1. Step 1: Check syntax line by line

   The line with std::cout << "Hi" << std::endl is missing a semicolon at the end.

2. Step 2: Identify compilation error cause

   Missing semicolon causes a syntax error during compilation, stopping the process.

3. Final Answer:

   Missing semicolon after std::endl -> Option D

4. Quick Check:

   Semicolon missing = syntax error [OK]

Hint: Check for missing semicolons after statements [OK]

Common Mistakes:

• Ignoring missing semicolon errors
• Thinking #include <string> is needed here
• Assuming return type is wrong

5. You have two C++ files: main.cpp and helper.cpp. You want to compile both and run the program. Which command correctly compiles and links both files into one executable named app?

hard

A. g++ main.cpp helper.cpp -o app

B. g++ main.cpp -o app helper.cpp

C. g++ -o app main.cpp; g++ helper.cpp

D. compile main.cpp helper.cpp app

Solution

1. Step 1: Understand compiling multiple files

   To compile multiple source files together, list them all in one g++ command.

2. Step 2: Check command syntax for linking

   g++ main.cpp helper.cpp -o app correctly lists both files and uses -o to name the executable.

3. Final Answer:

   g++ main.cpp helper.cpp -o app -> Option A

4. Quick Check:

   Multiple files compile = list all in one g++ command [OK]

Hint: List all source files in one g++ command to compile [OK]

Common Mistakes:

• Trying to compile files separately without linking
• Wrong order or syntax in command
• Using unknown 'compile' command