Getting Started in C: Introduction and Basics

INTRODUCTION TO C PROGRAMMING

Overview of C language

• C has played a pivotal role in the world of software development as a widely used general-purpose programming language. Let’s delve into its basics.
• A procedural programming language like C follows a set of commands or guidelines for the program’s efficient execution. 

Features of C programming language

• Procedural language
• Fast and Efficient
• Modularity
• Statically Typed
• General Purpose Language
• Rich Set of Built-in Set Operations
• Libraries with Rich Functions
• Middle-Level Language
• Portability
• Easy to Extend

All these features combined make it suitable for system programming, like operating systems or compiler development.

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What is the C language?

• Dennis Ritchie created C at Bell Laboratories in 1972.
• Despite its age, it remains popular due to its fundamental status in computer science.
• Its effectiveness and simplicity have made the C programming language renowned. Since it provides a fundamental understanding of programming, it is an ideal option for beginners.

History of C Language

• Development at Bell Labs: At AT&T Bell Labs between 1969 and 1973, Dennis Ritchie invented C. Ritchie and Ken Thompson initially created C as a systems programming language for the UNIX operating system.
• Evolution and Standardization: As C became more widely used outside of Bell Labs, it underwent a number of updates and enhancements. In 1989, the American National Standards Institute (ANSI) first standardized the C language, followed by the International Organization for Standardization (ISO) in 1990. These standardizations made it possible for systems to be portable and compatible with one another.
• Popularity and its Ubiquitous Nature: C’s efficiency, portability, and simplicity propelled its popularity across a range of industries. It became the preferred language for developing systems and applications, especially in the context of Unix. C greatly aided in the development of other programming languages, including C++, Objective-C, and eventually Java.
• Continued Relevance: Even with the introduction of more recent programming languages and paradigms, C remains relevant today. Fields requiring direct hardware interaction and performance optimization, such as system programming, embedded systems, and device drivers, still use it heavily.
• Impact on Operating Systems: C’s impact extended beyond the creation of applications. Due to its efficiency and low-level capabilities, developers chose it as the language of choice for developing operating systems. Some well-known operating systems, like Windows, Linux, and macOS, are written entirely or in part in C.
• Impact over history: C programming has left a significant legacy, influencing how programmers approach system design and programming in the software sector. Many software engineers believe that learning C is imperative for understanding computer architecture, memory management, and low-level programming concepts.

To learn more about the evolution of C programming language click here.

Why do people say that C is a middle-level language?

• Programmers can focus on the task at hand rather than worrying about the computer that their program will run on when they use C. Experts regard it as a middle-level language.

Why should we learn C programming?

• Many languages have borrowed syntax and features directly or indirectly from the C language.
• For example: Syntax of PHP, JavaScript, Python, etc.
• C++ is nearly a superset of the C language. (though only a few programs may be compiled in C, not in C++.)

Writing Your First Program

Syntax of C programming:

Input:

#include <stdio.h>
int main() {
   // printf() displays the string inside quotation
   printf("Hello, World!");
   return 0;
}

Output:

Hello, World!

BEGINNING WITH C PROGRAMMING

STRUCTURE OF A C PROGRAM

1. Header Files Inclusion: Line 1 [#include <stdio.h>]
2. Main method declaration: Line 2 [void main()]
3. Body of the main method: Line 3 to Line 6 [enclosed in {} ]
4. Statement: Line 4 [ printf(“Hello World!”); ]
5. Return Statement: Line 5 [return 0;][not used in the case of void main()]

Header Files Inclusion: Line 1 [#include <stdio.h>]

• This includes C function declarations and macro-definitions intended for sharing between several source files.
• A compiler invokes the preprocessor, a program that processes it, which begins with ‘#’.
• In the above example, the preprocessor copies the preprocessed code of’stdio.h’, to our file. In C, people call the.h files header files.

• Some of the C header files:

• stddef.h: It defines several useful types and macros.
• stdint.h: It defines the exact width of integer types.
• stdio.h: It defines core input and output functions.
• stdlib.h: It defines numeric conversion, functions, a pseudo-random network generator, and memory allocation.
• string.h: Defines string handling functions.
• math.h: Defines common mathematical functions.

Main method declaration: Line 2 [void main()]

• The entry point of a C program and its execution typically begin with the first line of main().
• The empty brackets indicate that the main doesn’t take any parameters.
• The void written before the main indicates the return type of the main().
• The main returns are a value that indicates the status of the program’s termination.
• This value, often an integer, serves as a signal to the operating system or calling process about how the program concluded its execution.
• For instance, a return value of zero usually indicates successful program termination without errors, while any non-zero value may denote different types of errors or abnormal termination states.
• By analyzing this return value, developers and system administrators can diagnose issues or verify the successful completion of the program.

Body of the main method: Line 3 to Line 6 [enclosed in {} ]

• It refers to statements that are part of the function.
• It can be anything like manipulations, searching, sorting, printing, etc.

Statement: Line 4 [ printf(“Hello World!”); ]

• Programmers give instructions to the compiler through statements.
• In C, you always terminate a statement with a semicolon (;). This practice distinctly marks the end of a logical statement, allowing the compiler to understand the separation between one instruction and the next.
• This syntax rule crucially maintains the structure and readability of C code, ensuring the correct interpretation and execution of statements.
• In this particular case, we use the printf() function to instruct the compiler to display “Hello World” text on the screen.

Return Statement: Line 5 [return 0;][not used in the case of void main()]

• The last part of any C function is the return statement.
• However, it is only utilized when initializing the program with int main() instead of void main().
• In the case of int main(),

1. The return statement and value depend only on the return type of the function.
2. The return statement in our program returns the value from the main().
3. The value of 0 typically means successful termination.
4. An operating system can determine the termination status of a program by checking its returned value.

IDEs for C programming

• Windows: Code Blocks and dev-cpp.
• Linux: The GCC compiler comes bundled with Linux. Developers can also use Code Blocks.
• macOS: macOS already has a built-in text editor where you can just write simple code without any complications and save it with the “.c” extension.

Applications of C programming language

• Operating Systems: Developers widely use C to develop operating systems such as Unix, Linux, and Windows.
• Embedded Systems: Companies and developers often choose C as a popular language for developing embedded systems such as micro-controllers, microprocessors, and other electronic devices.
• System Software: Developers use the C language to develop system software such as device drivers, compilers, and assemblers.
• Networking: Developers widely use C to develop networking applications such as web servers, network protocols, and network drivers.
• Database Systems: Developers use C to develop computer games due to its ability to handle low-level hardware interactions.
• AI: Developers utilize C to develop artificial intelligence and machine learning applications such as neural networks and deep learning algorithms.
• Scientific Applications: Researchers and developers employ C to develop scientific applications such as simulation software and numerical analysis tools.
• Financial Applications: Financial institutions and developers use C to develop financial applications such as stock market analysis and trading systems.