সহজ সরল প্রথম C প্রোগ্রাম টি লিখতে শিখুন

প্রথম C প্রোগ্রাম টি লিখতে শেখা

আমরা জানি C একটি উচ্চ-স্তরের প্রোগ্রামিং ভাষা এবং C প্রোগ্রামগুলি বাইনারি কোডে অনুবাদ করতে C কম্পাইলার (Compiler) দরকার হয় । বাইনারি কোড কম্পিউটার বুঝতে পারে এবং এক্সিকিউট করতে পারে। C প্রোগ্রাম লিখতে যে বেসিক জিনিসগুলি জানতে হবে --

• The #include directive
• Header files
• Comments
• The main() function
• The return statement
• The exit() function
• The newline character (\n)
• The void data type
• Translating a C program into an executable file
• Debugging

A Simple C Program
Let's have a look at our first C program, demonstrated in Listing 2.1. Later in this lesson you're going to write your own C program for the first time.

TYPE
 Listing 2.1. A simple C program.

  /* Simple C program */
  #include <stdio.h>

  main()
  {
     printf ("Suman, bah! This is my first C program.\n");
     return 0;
  }

This is a very simple C program, which is saved in a file called cprog01.c. Note that the name of a C program file must have an extension of .c. If you've installed a C compiler and set up the proper development environment, you should be able to compile this C program and make it into an executable file.

I set up my development environment in such a way that all C programs in this book can be compiled and made into DOS-based applications. For instance, cprog01.exe is the name of the DOS application made from cprog01.c. Note that .exe is included as the extension to the name of a DOS application program (that is, an executable file).

Also, on my machine, I save all the executable files made from the C programs in this book into a dedicated directory called C:\app. Therefore, if I type in cprog01 from a DOS prompt and press the Enter key, I can run the cprog01.exe executable file and display the message Howdy, neighbor! This is my first C program. on the screen. The following output is a copy from the screen:

C:\app> cprog01
Suman, bah! This is my first C program.
C:\app>

Summary
In this lesson you've learned the following:

• Some header files should be included at the beginning of your C program.
• Header files, such as stdio.h and stdlib.h, contain the declarations for functions used in your C program; for example, the printf() and exit() functions.
• Comments in your C programs are needed to help you document your programs. You can put comments anywhere you like in your programs.
• In ANSI C, a comment starts with the opening comment mark, /*, and ends with the closing comment mark, */.
• Every C program should have one but only one main() function. The program execution starts and ends with the main() function.
• The sequence of a carriage return and a line feed is carried out when the computer sees the newline character, \n.
• The return statement can be used to return a value to indicate to the operating system whether an error has occurred. The exit() function terminates a program; the argument to the function indicates the error status, too.
• The void data type can be used to modify the type of a return value for a function. Applying void to main() tells the operating system that the main() function does not return any value after termination.
• Compiling and linking are consecutive steps that have to be finished before an executable file is produced.
• Everybody, including yourself, makes mistakes in programming. Debugging is a very important step in your program design and coding.

In the next lesson you'll learn more about the essentials of C programs.