Syntax if expression block of statements else block

• Syntax:
if (expression)
{
Block of statements;
}
else
{
Block of statements;
}

The if Statement
• The if statement has the following syntax:
if ( condition
statement ;
if is a C
reserved word
The condition must be a
boolean expression. It must
evaluate to either true or false.
If the condition is true, the statement is executed.
If it is false, the statement is skipped.
)

Example: Program to check numbers
are equal or not
#include<stdio.h>
void main(void)
{
int first, second;
scanf ( “ %d %d “, &first, &second);
if ( first == second )
printf ( “Both numbers are equal \ n”);
else
printf ( “Numbers are not equal \ n”);
}

Nested if - elses
#include<stdio.h>
void main()
{
int i;
printf (“Enter either 1 or 2”);
scanf (“%d”,&i );
if(i==1)
printf (“ Gud morning”);
else
{
if(i==2)
printf (“ Gud afternoon”);
else
printf (“ Gud night”);
}
}

Forms of if
The if statement can take any of the following forms:
if ( condition )
do this ;
if ( condition )
{
do this ;
and this ;
}
if ( condition )
do this ;
else
do this ;
if ( condition )
{
do this ;
and this ;
}
else
{
do this ;
and this ;
}

) if ( condition )
do this ;
else
{
if ( condition )
do this ;
else
{
do this ;
and this ;
}
}
if ( condition )
{
if ( condition )
do this ;
else
{
do this ;
and this ;
}
}
else
do this ;

Program to print marks of students
#include<stdio.h>
#include<conio.h>
void main()
{
float marks
if (marks>90)
{
printf (“excellent”);
}
else if (marks>80&&marks<=90)
{
printf (“very good”);
}
else if(marks>70&& marks<=80)
{
printf (“good”);
}
else
{
if (marks >60 && marks<=70)
{
printf (“average”);
}
}
getch();
}

Switch Statement
• The control statement that allows to make a
decision from the number of choices is called
switch
• Also called switch-case-default
• The switch statement provides another way to
decide which statement to execute next
• The switch statement evaluates an expression,
then attempts to match the result to one of several
possible cases
• Each case contains a value and a list of statements
• The flow of control transfers to statement
associated with the first case value that matches

Rules of using switch case
• Case label must be unique
• Case label must end with colon