Many a times, we want a set of instructions to be executed in one
situation, and an entirely different set of instructions to be
executed in another situation. This kind of situation is dealt in
C programs using a decision control instruction. As mentioned
earlier, a decision control instruction can be implemented in C using:
(a) The if statement
(b) The if-else statement
(c) The conditional operators
(d) The else-if ladder (e) The switch statement
The if Statement
Like most languages, C uses the keyword if to implement the
decision control instruction. The general form of if statement looks
like this:
Syntax
if ( this condition is true )
{
execute these statements;
}
Flow Diagram of if statement
The if-else Statement
This is also said to be two way decision control statements. The general form of if statement looks like this:
Syntax
if ( this condition is true )
{
execute these statements ;
}
else
{
execute these statements;
}
Flow Diagram of if-else statement
Conditional operator (or) Ternary Operator
The conditional operator is unusual in that it takes three operands. The syntax of this operator is like this:
Condition ? Expression1 : Expression2;You can think of the conditional operator as if it were a function that works like this:
if ( Condition )
return Expression1;
else
return Expression2;
Example
int a=101,b=50,c;
c=a>b?10:20;
The else if ladder
This is also said to be two way decision control statements. The general form of if statement looks like this:
Syntax
if ( this condition is true )
{
execute these statements ;
}
else if ( this condition is true )
{
execute these statements ;
}
else if ( this condition is true )
{
execute these statements ;
}
.
.
.
else
{
execute these statements ;
}
Flow Diagram of else-if ladder
