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Conditional 'If'


'If' statements are used to examine the boolean values (true/false) and control the flow of program according to the boolean value.

A basic if statement can be expressed as following :

if ( condition )
{
   execute this statement if the condition is true
}


The statement can be further expressed as :

if ( condition )
{
   execute this statement if the condition is true
} else {
   execute this statement if the condition is false
}



Negation of condition uses '!' (exclamation mark)

If an exclamation mark is put before a condition, the boolean value of the statement is negated.

if ( !condition )
{
   execute this statement if the condition is false
}



OR boolean operator

OR boolean operator (||) can be used to join two or more statements and the joint statement will only return true if one or more of the statement is true.

if ( condition1 || condition2 )
{
   execute this statement if condition1 is true or condition2 is true or both are true
}



AND boolean operator

AND boolean operator (&&) can be used to join two or more statements and the joint statement will only return true if all of the statements is true.

if ( condition1 && condition2 )
{
   execute this statement if both condition1 and condition2 are true
}

Practice

using namespace std ;

string today = " " ;

string weather = " " ;


if ( today == "saturday" || today == "sunday" )

{

cout<<" Turn alarm off "<< endl ;

}

else

{

cout<<" Set alarm at 7am "<< endl ;

}


if ( today == "monday" && weather == "rainy" )

{

cout<<" I hate monday blues "<< endl ;

}

else

{

cout<<" Just a normal day "<< endl ;

}


Output

Set alarm at 7am
Just a normal day