Basic C Program Structure Practice Questions with Solutions

Introduction

Every C program follows a basic structure that tells the compiler how the program should be processed. Understanding this structure makes it easier to read, write, and debug C programs. In this chapter, you will practice important parts of a C program such as header files, main(), statements, braces, semicolons, comments, printf(), and return 0. The questions start with simple programs and gradually introduce more elements of C program structure. Basic C Program Structure practice questions with solutions to help you understand the concepts.

Q1. Write the Basic Structure of a C Program

Problem Statement

Write a simple C program that demonstrates the basic structure of a C program.

C Program

#include <stdio.h>

int main()
{
    printf("Hello, C!");

    return 0;
}

Sample Output

Hello, C!

Concepts Covered

• Header file
• main() function
• Curly braces
• Statement
• printf()
• return 0

Q2. Use the #include <stdio.h> Header File

Problem Statement

Write a C program that uses the stdio.h header file to display a message.

C Program

#include <stdio.h>

int main()
{
    printf("Learning C Program Structure");

    return 0;
}

Sample Output

Learning C Program Structure

Concepts Covered

• Preprocessor directive
• #include
• stdio.h
• printf()
• main()

Q3. Use Multiple Statements Inside main()

Problem Statement

Write a C program that displays three different messages using separate statements.

C Program

#include <stdio.h>

int main()
{
    printf("Welcome to C Programming\n");
    printf("I am learning C\n");
    printf("Practice makes programming easier");

    return 0;
}

Sample Output

Welcome to C Programming
I am learning C
Practice makes programming easier

Concepts Covered

• Multiple statements
• printf()
• \n
• Statement termination
• Program structure

Q4. Understand the Use of Semicolons

Problem Statement

Write a C program containing multiple statements, each ending with a semicolon.

C Program

#include <stdio.h>

int main()
{
    int a = 10;
    int b = 20;
    int sum = a + b;

    printf("Sum = %d", sum);

    return 0;
}

Sample Output

Sum = 30

Concepts Covered

• Semicolon ;
• Variable declaration
• Assignment
• Multiple statements
• printf()

Q5. Use Single-Line Comments

Problem Statement

Write a C program that uses single-line comments to describe different parts of the program.

C Program

#include <stdio.h>

int main()
{
    // Store two numbers
    int a = 15;
    int b = 25;

    // Calculate the sum
    int sum = a + b;

    // Display the result
    printf("Sum = %d", sum);

    return 0;
}

Sample Output

Sum = 40

Concepts Covered

• Single-line comments
• //
• Variables
• Arithmetic expression
• Program documentation

Q6. Use Multi-Line Comments

Problem Statement

Write a C program using a multi-line comment to describe what the program does.

C Program

#include <stdio.h>

/*
   This program calculates
   the area of a rectangle.
*/

int main()
{
    int length = 10;
    int width = 5;
    int area = length * width;

    printf("Area = %d", area);

    return 0;
}

Sample Output

Area = 50

Concepts Covered

• Multi-line comments
• /* */
• Variables
• Arithmetic operation
• Program documentation

Q7. Use return 0 in main()

Problem Statement

Write a C program that uses return 0 at the end of the main() function.

C Program

#include <stdio.h>

int main()
{
    printf("Program executed successfully.");

    return 0;
}

Sample Output

Program executed successfully.

Concepts Covered

• main()
• return 0
• Function return value
• Program termination
• printf()

Q8. Create a Program With Variables and Output

Problem Statement

Write a C program that stores a student’s name, age, and marks and displays them.

C Program

#include <stdio.h>

int main()
{
    char name[] = "Aman";
    int age = 15;
    float marks = 85.5;

    printf("Name: %s\n", name);
    printf("Age: %d\n", age);
    printf("Marks: %.1f", marks);

    return 0;
}

Sample Output

Name: Aman
Age: 15
Marks: 85.5

Concepts Covered

• Variables
• Character array
• Integer
• Float
• printf()
• Format specifiers
• Newline

Q9. Identify and Correct an Incorrect C Program Structure

Problem Statement

The following program contains structural and syntax mistakes. Find the mistakes and write the corrected program.

Incorrect C Program

#include <stdio.h>

int main()
{
    printf("Welcome to C")

    return 0;

Correct C Program

#include <stdio.h>

int main()
{
    printf("Welcome to C");

    return 0;
}

Sample Output

Welcome to C

Concepts Covered

• Curly braces
• Semicolon
• main()
• Syntax errors
• Basic program structure

Q10. Build a Complete Basic C Program

Problem Statement

Create a complete C program that displays a student’s information and calculates the total marks of three subjects.

C Program

#include <stdio.h>

int main()
{
    char name[] = "Rahul";
    int math = 80;
    int science = 75;
    int computer = 90;
    int total;

    total = math + science + computer;

    printf("Student Name: %s\n", name);
    printf("Math: %d\n", math);
    printf("Science: %d\n", science);
    printf("Computer: %d\n", computer);
    printf("Total Marks: %d", total);

    return 0;
}

Sample Output

Student Name: Rahul
Math: 80
Science: 75
Computer: 90
Total Marks: 245

Concepts Covered

• Complete C program structure
• Header file
• main()
• Variables
• Character array
• Arithmetic operation
• Multiple printf() statements
• Comments and formatting
• return 0

Key Takeaways

• A basic C program commonly contains a header file, main() function, statements, and a return statement.
• #include <stdio.h> provides declarations for standard input/output functions such as printf().
• Program execution begins from main().
• Curly braces { } define the body of the main() function.
• Most C statements end with a semicolon ;.
• printf() is used to display output.
• // is used for single-line comments.
• /* */ is used for multi-line comments.
• return 0; indicates successful completion of the main() function.
• Proper program structure makes C code easier to read, compile, and maintain.

FAQs

1. What is the basic structure of a C program?

A basic C program commonly contains header files, the main() function, declarations, executable statements, and a return statement.

2. Why is main() important in C?

main() is the function where execution of a standard C program begins.

3. What is the purpose of #include <stdio.h>?

It includes the standard input/output header file, which provides declarations for functions such as printf() and scanf().

4. Why is a semicolon used in C?

A semicolon marks the end of most C statements.

For example:

printf("Hello");

5. What are curly braces { } used for in C?

Curly braces define a block of code. The statements belonging to a function, loop, condition, or other block are placed inside them.

6. What is the purpose of return 0;?

Inside main(), return 0; returns the value 0 to the operating system and commonly indicates that the program completed successfully.

7. What are comments in C?

Comments are notes written inside source code for programmers. They are ignored by the compiler.

Single-line comment:

// This is a comment

Multi-line comment:

/*
   This is a
   multi-line comment
*/

Written by Shubhranshu Shekhar, who has trained 20000+ students in coding.

Rishabh Kumar