Programming Language | "C"

Introduction

In computing, C is a general-purpose programming language initially developed by Dennis Ritchie.

Like most imperative languages in the ALGOL tradition, C has facilities for structured programming and allows lexical variable scope and recursion, while a static type system prevents many unintended operations.

A Simple C Program

Example:

#include<stdio.h>

#include<conio.h>

int main ()

{

   clrscr();

   printf(“Welcome to C

           Language”);

   getch();

   return 0;

}

Output :

Welcome to C Language

In the above program:

The first line of the program contains a preprocessing directive, indicated by “#include”

This is an instruction to the compiler (a program that translates C code into such information that a computer can understand.)

It tells the compiler that another file is needed to compile the program; in this case, stdio.h and conio.h are used.

stdio.h is a standard input/output file that includes definitions for common input and output methods.

conio.h is a header file used mostly by MS-DOS compilers to provide console input/output.

The "main" has a couple of parentheses, which are an indication to the compiler that this is a function.

The two curly brackets { }, properly called braces, are used to specify the limits of the program itself.

“clrscr()” is used to clear the previous output screen.

“printf()” is used to print the contents of the parentheses, in this case: the output is “Welcome to C Language”

In C, semi-colon (;) is used to signal to the compiler that a line is complete.

In this program getch() is just used to pause a program after it prints “Welcome to C Language.”

Without this, the screen would just flash the statement and then close.

return

In C, functions often return values.

Some functions return numbers or characters.

The main() function should always return either zero or one.

This is what the program above will look like when it runs on your screen:

The History of C

C was developed at Bell Laboratories in 1972 by Dennis Ritchie.

In 1983, the American National Standards Institute (ANSI) established a committee to provide a modern, comprehensive definition of C.

The resulting definition, the ANSI standard, or "ANSI C", was completed late in 1988.

Today C is in widespread use with a rich standard library of functions.

Why Use C?

Mainly because it produces code that runs nearly as fast as code written in Assembly Language.

Many different kinds of software are written in C:

Language compilers and interpreter

Device drivers

Telecom applications

Network programming

Digital signal processing applications

Database applications

Text editors

Operating systems

Evaluation of C Programming

C is often called a "Pseudo high level language" or a "Middle level language."

This is not because of its lack of programming power but because of its capability to access the system's low level functions.

C instructions are compiled to assembly code; therefore, depending on the complexity of the code and on the compiler optimization capabilities, C code may run as fast as assembly code.

C is prized for its efficiency, and is the most popular programming language for writing system software.

Execution of C Programs

There are four steps for creating and executing a program in C:

Creating a Program:

Programs are often written using an Integrated Development Environment (IDE) such as Microsoft Visual Studio.

Programs can be written using only a basic text editing program like notepad, but Microsoft Visual Studio has many useful features, such as:

Debugging capabilities

An integrated compiler

Code navigation tools

Compiling the Program:

The next step is to compile the program.

A C compiler converts executable code to object code.

Object code consists of binary instructions for the computer to execute.

Linking a Program to a Library:

The object code of a program is linked with libraries that are needed for the execution of a program.

The linker is used to link the program with libraries.

It creates a file with '.exe' extension.

Execution of the Program:

The final executable file is then run by the dos command prompt.

C Programming Advantages

C is a small, efficient, powerful and flexible language.

C is close to computer H/W (architecture).

C is standardized, making it more portable compared to other languages.

It contains libraries.

Many other languages borrow syntax from C syntax.

Example:

Java, JavaScript, Perl.

The Future of C

C is an important language which will continue to be so.

Many other languages are based on C, so learning the principles of C help one understand and learn additional languages.

C is a better option when it comes to programming device drivers, embedded applications and utility programs.