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Hello world program in C

4 min 23 sec read

There might be two reasons you have landed on this C tutorial for beginners.

1) You might want to explore the basics of C programming.

2) You are looking to write your first hello world program in C.

Trust me learning C programming is the best decision you have ever taken in your life. The skills you need to become the best computer programmer in this world start with C programming. C programming is also called as "Mother of all languages".

We will guide you through each and every concept step by step.  Okay, So lets begin with the very basic C program. Most programming languages like C++, Java adopts syntax of C language. That's why C programming is also called as the mother of all Programming languages.

Basic Syntax


/* Preprocessor Declaration */
/* Main Function */
returntype main() 
{
program statements to be executed.
} 

1) Preprocessor Declaration: This section includes all the necessary libraries required in our C program. These libraries include many functions which we can use in our program and this also makes the life of developers easy.

2) main(): main function is the entry point of the program.

Example :-

Let's write our first hello world program in C which illustrates the syntax of C programming.

/* Hello World program in C */
#include 
#include 
int main()
{  
printf("hello world program in c");  
return 0;  
}

Explanation :-

#include 

stdio.h  is the standard input-output library that contains the functions like printf() which are then used to print the statements in a C  program.

#include 

conio.h is the console input-output library that contains the functions like getch() which is basically used to hold the screen. In the next point, we have explained the purpose of getch() function also.

void main()

The main() function is the entry point of every program in the C language. The void keyword specifies that it returns no value.

printf()

The printf() function is used to print the data on the output console.

getch() 

The getch() function is used to hold the screen unless and until the user presses any key like "Enter" or any key. Try removing getch() in the program and see the effect.

Comments

Comments are used to describe the purpose of statements in the program. It is the best practice to include comments every time you write the program. Suppose there is a team of 20 developers in a company which is working on the same project. Then each and every developer should understand what you have written in your code. This is how comments can be useful in live projects.

/* This is a C Comments Statement */

Example:-

/* C First program Comment */

/* C Libraries */
#include    
#include   

/* Main Function 
void main()
{ 

/* Print the Hello world */ 
printf(" hello world program in c ");  
  
getch();  
}  

What are Identifiers in C?

A C identifier is a name used to identify a variable, function, or any other user-defined item. An identifier in C starts with a letter A to Z, a to z, or an underscore '_' followed by zero or more letters, underscores, and digits (0 to 9). C programming does not allow punctuation characters such as @, $, and % within identifiers. C programming is a case-sensitive programming language. Thus, Programming and programming are two different Identifiers in C.

abc , _abc , abc_123 are valid tokens
whereas,
$abc,#abc,abc$ are not valid tokens . 

Tokens in C

A C program consists of various tokens and token is either a keyword, an identifier, a constant, a string literal, or a symbol. There are 5 tokens in the given example above.

printf                           --> 1st token
(                                --> 2nd token
"Hello world program in C"                 --> 3rd token
)                                --> 4th token
;                                --> 5th token

I hope you have now a better understanding of how to write your very first Hello World program in C.

 

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