As we know that any c program is made up of 1 or more then 1
function. Likewise it use some functions for input output process. The most
common function are printf() and scanf().
Printf() function :
Printf() function is
use to display something on the console or to display the value of some variable on the console The general
syntax for printf() function is as follows
printf(<”format string”>,<list of
variables>);
To print some message on the screen
Printf(“God is great”);
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This will print message “God is great” on the screen or console.
To print the value of some variable on the screen
Integer Variable :
int a=10;
printf(“%d”,a);
Here %d is format string to print some integer value
and a is the integer variable whose value will be printed by printf() function.
This will print value of a “10” on the screen. You can make this output
interactive by writing them
Int a=10;
Printf(“a=%d”,a);
This will print “a=10” on the
screen
To print multiple variable’s
value one can use printf() function in following way.
Int p=1000,r=10,n=5;
Printf(“amount=%d rate=%d yeat=%d”,p,r,n);
This will print “amount=1000
rate=10 year=5” on the screen
Float Variable :
Float per=70.20;
printf(“Percentage=%f”,per);
Here %f is format string to print some float(real)
value and per is the float variable whose value will be printed by printf()
function. This will print value of a “Percentage=70.20” on the screen.
Character Variable:
char ans=’Y’;
printf(“Answer=%c”,ans);
Here %c is format string to print single character value and ans is the
character variable whose value will be printed by printf() function. This will
print value of a “Answer=Y” on the screen.
Suppose we want to print “Amar”
on the screen with character variable
Char c1=’A’,c2=’m’,c3=’a’,c4=’r’ ;
Printf(“Name = %c %c %c %c”, c1,c2,c3,c4);
This will print “Name=A m a r” on the screen.
You can use single printf()
function to print different data type variable’s value also.
Example
Int rno=10;
Char res=’P’;
Float per=75.70;
Printf(“Rollno=%d Result=%c
Percentage=%f”,rno,res,per);
This will print message
“Rollno=10 Result=P Percentage=75.70” on the screen.
Scanf() Function :
Scanf() function is use to read
data from keyboard and to store that data in the variables.
The general syntax for scanf ()
function is as follows.
Scanf(“Format String”,&variable);
Here format string is used to define which type of data it is taking as
input this format string can be %c
for character, %d for integer
variable and %f for float variable.
Where as variable the name of memory location or name of the variable and &
sign is an operator that tells the compiler the address of the variable where
we want to store the value. One can take multiple input of variable with single
scanf() function but it is recommended that there should be one variable input
with one scanf() function.
Scanf(“Format string1,format
string2”,&variable1,&variable2);
For Integer Variable
:
Scanf (“%d”,&rollno);
For Float Variable :
Float per;
Printf(“Enter Percentage=”);
Scanf(“%f”,&per);
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Single character input – the getchar function :
Single
characters can be entered into the computer using the “C” library function
getchar. The getchar function is a part of the standard “C” language I/O library. It returns a single
character
from a standard input device (typically a keyboard). The
function does not required any arguments through a pair of empty parentheses
must follow the word getchar.
In general terms, a reference to the getchar function is
written as.
Character
variable=getchar();
Where
character variable refers to some previously declared character variable.
A “C”
program contains the following statements.
char c;
c=getchar();
The first
statement declares that c is a character type variable. The second statement causes a single
character to be entered from the standard input device and then assigned to c.
If an
end-of file condition is encountered when reading character with the getchar
function, the value of the symbolic constant EOF will automatically be
returned. The detection of EOF in this manner offers a convenient way to detect
an end of file, whenever and wherever it may occur. Appropriate corrective action can be taken. The
getchar function can also be used to read multicharacter strings, by reading
one character at a time a multiples
loop.
Single character output – The putchar function:
Single
character can be displayed (i.e. written out of the computer) using the C
library function putchar.The putchar function, like getchar is a part of the
standard “C” language I/O library. It transmits a single character to a
standard output device. The character
being transmitted will normally be represented as a character-type variable. It must be expressed as an argument to the
function, enclosed in parentheses following the word putchar. In general a
reference to the putchar function is written as
Putchar (character variable)
Where
character variable refers to some previously declared character variable.
A “C”
program contains the following statements.:
char c=’a’;
putchar(c);
The first
statement declares that c is character type variable. The second statement
causes the current value of c to be transmitted to the standard output device
where it will be displayed.
The putchar function can be used to output a
one-dimensional, character type array.
Each character can then be written separately within a
loop.
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