Basic I/O Functions
- In C, there are no special keywords to
perform input/output operations.
- These operations are carried out by
using library functions.
- All console I/O functions produce only
text based outputs.
- However most compilers include screen
control and graphics functions in their libraries.
The important task of any programming
language is to handle input/output. C supports a set of library functions to
handle I/O.
For I/O operations printf() and scanf()
functions are used. These are formatted functions that allow the input read
from keyboard and output displayed on the monitor to be formatted as per our
requirements.
printf()
Its name comes from print formatted. Format specifiers request that the argument
be formatted and inserted into the string.
printf(“format
specifier”,list of variables);
|
scanf()
It accepts the data from keyboard, formats it
in a certain way as specified by the format specifiers and stores it in a
variable.
scanf(“format specifier”,list of addresses of
variables);
|
Preprocessor
· Preprocessor
directives are the instructions given to the compiler.
· Preprocessor
directives begin with # (hash).
· Preprocessor
directives are often placed in the beginning of a program before the main() is
declared.
· They are not
translated into machine language, but are operated upon directly by the
compiler before the compiling process begins.
C Library
Every C program consists of modules of pieces
of code called functions. A function aims at accomplishing a specific task.
With in a program you can write your own functions or you can use the functions
that are provided by C library.
C library provides a rich collection of
functions to the programmer for most common programming tasks. The functions
provided by the C program are a part of C standard library.
How to use library files.
#include<header file name>
|
#include<stdio.h>
|
#include<conio.h>
|
#include<math.h>
|
Some
Important Library Functions:
- main() – Start of program
- clrscr() – Clear screen
- getch() – To display output
- gets() – To read string
Structure of C Program
|
//
name of the program
Or
/*
name of the program, name of author, date, brief description, modification
details etc.*/
#include<headerfiles>
#define
constants
Function prototype;
/* if you declared your own function*/
return
type main()
{ /*
prog begins*/
Declaration of local variables;
Executable part;
return;
} /*
end of main() */
User
define function()
{
Function
code;
}
|
Compiling And Running
Program
Source File
This is single program file written by
programmer.
This file has names which end in .c by
convention.
Compiler
It translates the program written by user
into binary format which can be directly understood by underlying operating
system.
Object File
These are consists of function definitions in
binary form, but are not executable by themselves.
These are created from source code file.
Linker
It links together a
number of object files to produce an executable file.
Executable File
These are produce as
the out of program. It generally ends with .exe.
