Basic Syntax Structure | Introduction To C

1. Introduction

The C programming language is a versatile and powerful language that is widely used in various applications, from system programming to game development. In this tutorial, we will cover the basic syntax and structure of a C program, helping you understand how to write and execute simple C programs.

2. Basic Structure of a C Program

Every C program consists of one or more functions, and the most common function is the main() function. The main() function is the entry point of any C program. Here is a simple C program:

#include <stdio.h>

int main() {
    printf("Hello, World!\n");
    return 0;
}

Let's break down this program:

#include <stdio.h> - This is a preprocessor directive that includes the Standard Input Output library, which is necessary for using the printf() function.
int main() - This is the main function where the program execution begins.
printf("Hello, World!\n"); - This line prints the text "Hello, World!" to the console.
return 0; - This line indicates that the program ended successfully.

3. Comments

Comments are used to explain code and are ignored by the compiler. There are two types of comments in C:

Single-line comments: These start with // and continue to the end of the line.
Multi-line comments: These start with /* and end with */.

// This is a single-line comment
/*
    This is a
    multi-line comment
*/

4. Data Types and Variables

In C, variables are used to store data. Each variable must be declared with a specific data type. Common data types include:

int - Integer type
float - Floating point type
char - Character type

Here is an example of declaring and using variables:

#include <stdio.h>

int main() {
    int age = 25;
    float height = 5.9;
    char initial = 'A';

    printf("Age: %d\n", age);
    printf("Height: %.1f\n", height);
    printf("Initial: %c\n", initial);

    return 0;
}

Age: 25
Height: 5.9
Initial: A

5. Operators

C supports various operators to perform operations on variables and values. Some common operators include:

Arithmetic Operators: +, -, *, /, %
Relational Operators: ==, !=, >, <, >=, <=
Logical Operators: &&, ||, !
Assignment Operators: =, +=, -=, *=, /=, %=

Here is an example using some arithmetic operators:

#include <stdio.h>

int main() {
    int a = 10, b = 20;
    int sum = a + b;
    int diff = a - b;
    int prod = a * b;
    int div = b / a;
    int mod = b % a;

    printf("Sum: %d\n", sum);
    printf("Difference: %d\n", diff);
    printf("Product: %d\n", prod);
    printf("Division: %d\n", div);
    printf("Modulus: %d\n", mod);

    return 0;
}

Sum: 30
Difference: -10
Product: 200
Division: 2
Modulus: 0

6. Control Structures

Control structures are used to control the flow of a program. Common control structures in C include:

Conditional Statements: if, if-else, switch
Loops: for, while, do-while

Here is an example using an if-else statement:

#include <stdio.h>

int main() {
    int num = 10;

    if (num > 0) {
        printf("The number is positive.\n");
    } else {
        printf("The number is not positive.\n");
    }

    return 0;
}

The number is positive.

7. Functions

Functions are blocks of code that perform a specific task. They help to make code modular and reusable. Here is an example of a simple function:

#include <stdio.h>

void greet() {
    printf("Hello, World!\n");
}

int main() {
    greet();
    return 0;
}

Hello, World!

8. Conclusion

This tutorial covered the basic syntax and structure of a C program. We discussed the basic structure, comments, data types, variables, operators, control structures, and functions. With this knowledge, you should be able to write and understand simple C programs. Practice writing your own programs to become more proficient in C.

Introduction to C - Basic Syntax and Structure