quick guide

It may so happen that in program we want more than
one statement to be execute if the expression following
IF is satisfied.If such multiple statements are to be
execute then they must be placed within a pair of
braces as illustrated in the following example.
Example:3 /* calculation of Bonus*/

main()
{
int bonus, cy, yoi,yr_of_ser;
printf("Enter current Year and Year of joining");
scanf(%d%d",&cy,&yoi);
yr_of_ser=cy-yoi;
if(yr_of_ser>3)
{
bonus=2500;
printf("Bomus=Rs. %d",binus);
}
}
Observe that here the two statements to be executed
on satisfaction of the condition have been enclosed
within a pair of braces. If a pair of braces is not
used then the C compiler assumes that the programmer
wants only the immediately next statement after the if
to be execute on satisfaction of the condition. In the
other words we can say that the default scope of the IF
statement is the immediately next statement after it.

The IF-ELSE Statement:

if. . .else statement is an extension of the simple
IF statement.

The general form is:

if(test condition)

{

True-Block statement(s)

}

else

{

False-Block statement(s)

}

statement -x;

Points to be remembered:

1. The group of statements after the IF up to and not
including the ELSE is called an "IF BLOCK". Similarly,
the statements after the ELSE form the "ELSE BLOCK".
2. Notice that the ELSE is written exactly below the IF.
The statements in the IF block and those in the ELSE
block have been indented to the right.
3. Had there been only one statement to be executed in
the IF block and only one statement in the ELSE block
we would have dropped the pair of Braces.
4. As with the If statement, the default scope of ELSE
is also the statement immediately after the ELSE. to
override this default scope a pair of braces must be
used.

Let us consider an example of counting the number of
boys and girls in a class. We can use code 1 for boys
and 2 for girls.

- - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - -

if(code==1)

boy=boy+1;

if(code==2)

girl=girl+1;

- - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - -

Example:4

main()

{
int a=300,b=10,c=20;

if(!(a>=400))

b=300;

c=200;

printf("b=%d c=%d",b,c);

}

OUTPUT: b=300 c=200

Explanation: The condition (a>=400) evaluates to
FALSE since a is neither equal to nor greater than
400. The condition is therefore replaced by '0'.But
the NOT operator (!) negates the result of this
condition. This means it reverses the result
of the condition (0) to 1. Thus the If gets reduced
to,

if(1)

b=300;

obviously, b=300 would get executed, followed by c=200,
hence the output.


Example:5

main()

{

if(!3.14)

printf("rama is a good boy");

else

printf("Rama and Krishna are friends");

}

OUTPUT:
Rama and Krishna are friends

Explanation: 3.14 being a positive number, is a truth
value, and on negating it using the ! operator it results
into a '0'.thus the result of the condition is FALSE,
hence the second printf() is executed.

Example:6

main()

{

float a=12.25, b=13.65;

if(a=b)

printf("a and b are equal");

else

printf("a and b are not equal");

}

OUTPUT:
a and b are equal

Explanation: To begin with a and b are not equal. The
catch here is the assignment operator used in the if
statement. it simply assigns the value of b to a, and
hence the condition becomes,

if(13.65)
The condition evaluates since the value is a
non-zero value,so the printf() may evaluate, Hence the
result.