Module 0: Introduction to Programming

Table of Contents

• IDE (Integrated Development Environment)

• Introduction to the C Language

  • Statement
  • "Hello, world."
  • Program Structure
  • Comments

• Keywords and Identifiers

  • Keywords
  • Identifiers

• Variables

  • Introduction to Variables
  • Variable Declaration and Definition
  • Assigning a Value
  • Initializing a Variable

• Constants and Literals

  • Constants and Literals
  • Defining a Constant

• Basic Data Types

  • Integer Type
  • Real Number (floating point) Type
  • Character Type

• Basic Input and Output

  • Basic Output
  • Basic Input

• Operators

  • Assignment Operators
  • Arithmetic Operators
  • Increment and Decrement Operators
  • Relational Operators
  • Logical Operators
  • Bitwise Operators
  • Combined Operators
  • Other Operators

IDE (Integrated Development Environment)

Before we start coding, we need an IDE to simplify the coding process. What is an IDE? To put it simply, an IDE or Integrated Development Environment is a code editor application that also provides a compiler. Here are some IDEs for the C language that are commonly used:

• DevC++
• CodeBlocks

Introduction to the C Language

Statement

In a program, a statement is a command that instructs the computer to carry out a certain action, such as displaying something to the computer.

If we were to put it into an analogy, when we speak to someone, we use a language that we both understand, so that we can convey what we want to tell them. That's what a statement is. Conveying a message to someone is akin to a statement in a program.

"Hello, world."

Let's start by creating a simple program, displaying the iconic sentence "Hello, world!" to the screen (console). This is the code for program:

#include <stdio.h>  

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

Copy the code above to your IDE, and then compile and run. The compilation process will result the following output.

Hello, world!

Program Structure

To explain how the above program works, let's divide the code into several parts.

Header File

The first line in the code is called the preprocessor directive. The preprocessor used in this case is '#include'

The '#include' preprocessor tells the preprocessor to insert the contents of another file, the header file <stdio.h> into the source code at the point where the #include directive is found. The <stdio.h> header file is a built-in C library that contains important functions needed by the program. In this case, the header file provides the 'printf()' function to display the sentence “Hello, world!”. Without the library, the program can't be compiled.

main() Function

The main() function in the code is used from the 3rd line until the 7th line.

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

In every C program, the main() function must always be there. This is because the execution of a code starts from the beginning of the main() function.

• The 3rd line shows the name and the return type of the function. int is the type of return for the function named main(). Then the symbol '{' denotes the start of the main() function
• Line 4 through 6 contains the body of the main()function
• Line 8 contains the symbol '}' which denotes the end of the main() function. Essentially, the body of a function will always be in-between the '{}' symbols.

Whitespace

We can see that line 2 and 4 is empty (no characters whatsoever). This is called a whitespace. Whitespace is the empty area in a code, usually used to make the code more readable.

There are three kinds of whitespace, space, tab, and new line. Line 2 and 4 is an example of a new line whitespace.

Statement

In the main() function, there are two statements in line 5 and line 6. Most statements ends with a semicolon (;).

printf("Hello, world!\n");  
return 0;  

The statement in line 5 instructs the program to call the printf() function. The printf() function is a function provided in the library header <stdio.h> and is used to display an output to the console (screen). In this case, the printf() function receives a string argument “Hello, world!\n”. The ‘\n’ in the string is a special character used to print a new line.

While the statement in line 6 is called a return statement. The command return 0 in the function main() is used to end the program and signalizes that the program has been successfully executed.

Comments

Komentar (comment) adalah bagian dari program yang tidak akan dieksekusi. Komentar sangat berguna untuk mendeskripsikan program yang dibuat, misalnya saja untuk menjelaskan bagian dari kode agar mudah dipahami oleh programmer lainnya. Terdapat dua jenis komentar dalam bahasa C.

Komentar Single-Line

Seperti namanya, komentar single-line hanya bekerja pada satu baris. Komentar single-line diawali dengan simbol // . Semua karakter (pada satu baris) dibelakang simbol // akan diabaikan.

// Ini adalah komentar single-line  
  
// Fungsi untuk mencetak ke layar  
printf("HALO\n");  

Komentar Multi-Line

Sedangkan komentar multi-line dapat bekerja pada lebih dari satu baris. Pasangan simbol /* dan */ digunakan untuk membuat komentar multi-line. Semua karakter yang berada di antara dua simbol tersebut akan diabaikan.

/* 
Ini adalah komentar multi-line 
Semua yang berada di sini akan 
diabaikan 
*/  

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