First C Program and Header files

First C Program

Before starting the abcd of C language, you need to learn how to write, compile and run the first c program.

To write the first c program, open the C console and write the following code:

#include <stdio.h>    
int main(){    
printf("Hello C Language");    
return 0;   

#include includes the standard input output library functions. The printf() function is defined in stdio.h .

int main() The main() function is the entry point of every program in c language.

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

return 0 The return 0 statement, returns execution status to the OS. The 0 value is used for successful execution and 1 for unsuccessful execution.

How to compile and run the c program

There are 2 ways to compile and run the c program, by menu and by shortcut.

By menu

Now click on the compile menu then compile sub menu to compile the c program.

Then click on the run menu then run sub menu to run the c program.

By shortcut

Or, press ctrl+f9 keys compile and run the program directly.

You will see the following output on user screen.

c program output

You can view the user screen any time by pressing the alt+f5 keys.

Now press Esc to return to the turbo c++ console.

  1. C Programming Basics - Learn C Programming & C programs

Header files contain the set of predefined standard library functions that we can include in our c programs. But to use these various library functions, we have to include the appropriate header files.

Let us see in detail how the compiler interprets the line :


Here, # is a pre-processor directive which tells us that this is the line which must be pre-processed by pre-processor.

include tells us that there is a filename ahead which must be included at the top of our program. Preprocessor simply copies contents of file stdio.h in our code.

<> – Angled brackets defines where to search for header files.

stdio.h – is the file to be included in our program so that we can use built-in functions in our program. These built-in functions are only declared in such header files and not defined.

Apart from method or class declarations, header files also contain predefined macros, data type definitions, etc.

When you call a built-in function, at compile time compiler compares your calling statement with function prototype(which is in the header file) and if the return type, function name, number of arguments, type of arguments are same then only the result of comparison is said to be satisfying otherwise compiler gives you errors.

We can create our own header files as well. But they are specified in between double quotes instead of angular brackets which will convene to make programming easier.

If you have a standard set of instructions that you want to insert in a lot of programs that you are writing then you can do it using the #include statement.

The # symbol at the start stipulate that this isn’t a C statement but one for the C pre-processor which looks at the text file before the compiler gets it. The #include tells the pre-processor to read in a text file and treat it as if it was part of the program’s text. For example:

#include “copy.txt”

could be used to include a copyright notice stored in the file copy.txt. However, the most common use of the #include is to define constants and macros. The C pre-processor is almost a language in its own right For example if you define the identifier NULL as:

#define NULL 0

then whenever you use NULL in your program the pre-processor substitutes 0. In most cases you want these definitions to be included in all your programs and so the obvious thing to do is to create a separate file that you can #include.

This idea of using standard include files has spiraled out of all proportions. Now such include files are called header files and they are distinguished by ending in the extension .h. A header file is generally used to define all of the functions, variables, and constants contained in any function library that you might want to use.

There are many header files in C programming language and there all header files have their own different functionalities…

List of all header file of c language as below.


1 stdio.h Input/Output Functions
2 conio.h console input/output
3 assert.h Diagnostics Functions
4 ctype.h Character Handling Functions
5 cocale.h Localization Functions
6 math.h Mathematics Functions
7 setjmp.h Nonlocal Jump Functions
8 signal.h Signal Handling Functions
9 stdarg.h Variable Argument List Functions
10 stdlib.h General Utility Functions
11 string.h String Functions
12 time.h Date and Time Functions
13 complex.h A set of function for manipulating complex numbers
14 stdalign.h For querying and specifying the alignment of objects
15 errno.h For testing error codes
16 locale.h Defines localization functions
17 stdatomic.h For atomic operations on data shared between threads
18 stdnoreturn.h For specifying non-returning functions
19 uchar.h Types and functions for manipulating Unicode characters
20 fenv.h A set of functions for controlling floating-point environment
21 wchar.h Defines wide string handling functions
22 tgmath.h Type-generic mathematical functions
23 stdarg.h Accessing a varying number of arguments passed to functions
24 stdbool.h Defines a boolean data type