C is a general-purpose procedural programming language known for its efficiency and low-level memory access. It is widely used in system programming, embedded systems and performance-critical applications due to its speed, portability and close interaction with hardware.
Writing First Program in C Language
This simple program demonstrates the basic structure of a C program.
#include <stdio.h>
int main(void)
{
// This prints "Hello World"
printf("Hello World");
return 0;
}
Output
Hello World
Structure of the C program
The structure of a C program is as follows:
Header Files Inclusion - Line 1 [#include <stdio.h>]
The first component is the Header files in a C program. A header file is a file with extension .h which contains C function declarations and macro definitions to be shared between several source files. All lines that start with # are processed by a preprocessor which is a program invoked by the compiler. In the above example, the preprocessor copies the preprocessed code of stdio.h to our file.
Some of the C Header files:
- stddef.h - Defines several useful types and macros.
- stdint.h - Defines exact width integer types.
- stdio.h - Defines core input and output functions
- stdlib.h - Defines numeric conversion functions, pseudo-random number generator, and memory allocation
- string.h - Defines string handling functions
- math.h - Defines common mathematical functions.
Main Function Declaration - Line 2 [int main()]
The next part of the above C program is the main() function. It is the entry point of a C program. The empty brackets indicate that the main doesn't take any parameter (See this for more details). The int that was written before the main indicates the return type of main() and the value returned by the main indicates the status of program termination.
Body of Main Function - Line 3 to Line 6 [enclosed in {}]
The body of the main function in a C program consists of the statements it executes, such as manipulation, searching, sorting, and printing. It is defined by a pair of curly brackets {}, and all function definitions start and end with these brackets.
Comment - Line 7[// This prints "Hello World"]
The comments are used for the documentation of the code or to add notes in your program that are ignored by the compiler and are not the part of executable program .
Statement - Line 4 [printf("Hello World");]
Statements are the instructions given to the compiler. In C, a statement is always terminated by a semicolon (;). In this particular case, we use printf() function to instruct the compiler to display "Hello World" text on the screen.
Return Statement - Line 5 [return 0;]
The last part of the above C function is the return statement (return statement becomes optional if the return type of the method is void). The return statement specifies the value returned by a function—here, from main()—to indicate the program’s exit status to the operating system. A return value of 0 typically signifies successful execution, while non-zero values indicate errors or abnormal termination.
Execute C Programs
To run this program, you need to create a development environment for C. A development environment mainly consists of a text editor, which is used to write the code, and a compiler that converts the written code into the executable file. Refer to this article - Setting Up C Development Environment
Application of CÂ Language
C language is being used since the early days of computer programming and still is used in wide variety of applications such as:
- C is used to develop core components of operating systems such as Windows, Linux, and macOS.
- C is applied to program embedded systems in small devices such as washing machines, microwave ovens, and printers.
- C is utilized to create efficient and quick game engines. For example, the Doom video game engine was implemented using C.
- C is employed to construct compilers, assemblers, and interpreters. For example, the CPython interpreter is written partially using C.
- C is applied to develop efficient database engines. The MySQL database software is implemented using C and C++.
- C is employed to create programs for devices and sensors of Internet of Things (IoT). A common example is a house automation system comprising temperature sensors and controllers that is often prepared with C.
- C is employed for creating lightweight and speedy desktop applications. The widely used text editor Notepad++ employs C for performance-sensitive sections.
Read about Difference between C and C++ from here
History Of C
C is a general-purpose procedural programming language developed by Dennis Ritchie in 1972 at Bell Labs to build the UNIX operating system. It provides low-level memory access, high performance, and portability, making it ideal for system programming. Over the years, C has evolved through standards like ANSI C, C99, C11, and C23, adding modern features while retaining its simplicity. Read more about history here.
