C++ Tutorial 03 - if /else if /nested if

Relational and logical operators in C++ compare two or more operands and return true or false values based on their results.

Comparison/Relational Operators:

Comparison operators are binary operators that evaluate a condition and return 1 if it is logically true and 0 if it is logically false.

Equal	a == b
Not Equal	a != b
Greater than or Equal	a >= b
Less than or Equal	a <= b
Less than	a < b
Greater than	b > a

 

Logical Operators:

To determine whether an expression is true or false, we employ logical operators. If the expression is true, it will return 1, but if it is false, it will return 0.

All expressions must be true.	(a==b) && (c>d)
Any expression should be true.	(a==b)  || (c>d)
Not true	!a

These operators are used in decision-making.

if

                                               

Code 1 – if

• If you are absent for more than three days, can’t sit the final exam.

#include <iostream>

using namespace std;

int main()

{

//declare variables

int intNoDaysAbsent;

 

//ask for attendance

cout<<"How many days candidate was absent? ";

//user enters no. of days absent

cin>>intNoDaysAbsent;

if (intNoDaysAbsent>3)

{

cout<<"Candidate has not attend 80% of the lectures."<<endl;

cout <<"Sorry, candidate is not eligible to sit the ESE."<<endl;

return 0;

}

cout<<"Candidate is eligible to sit the ESE.";

 

return 0;

}

 

 

Code 2 – nested if

• If you are absent more than three days and CA Marks less than 50, can’t sit the final exam.

#include <iostream>

using namespace std;

int main()

{

const float fltCARatio = 0.3;

//declare variables

int intCAMarks = 0;//store Continuous Assessment marks (out of 100)

int intNoDaysAbsent;

//ask for attendance

cout<<"How many days candidate was absent? ";

//user enters no. of days absent

cin>>intNoDaysAbsent;

if (intNoDaysAbsent<=3)

{

cout<<"Enter candidate's CA marks (out of 100) :";

cin>>intCAMarks;

    if (intCAMarks<0 || intCAMarks>100)

    {

    cout<<"Error: CA marks should be between 0 - 100."<<endl;

    return 0;

    }

    else

        if(intCAMarks<50)

        {

        cout<<"Candidate has not got 50% of the CA marks"<<endl;

        cout<<"Sorry, candidate is not eligible to sit theESE."<<endl;

        return 0;

        }

        else

        cout<<"Candidate is eligible to sit the ESE."<<endl;

}

else{

cout<<"Candidate has not attend 80% of the lectures."<<endl;

cout <<"Sorry, candidate is not eligible to sit the ESE."<<endl;

return 0;

}

 

return 0;

}

 

Code 3 – else if

• Finally, calculate the final grade of the subject.

#include <iostream>

using namespace std;

int main()

{

//declare constants

const float fltCARatio = 0.3;

//declare variables

int intCAMarks = 0;//store Continuous Assessment marks (out of 100)

int intESEMarks = 0;

int intNoDaysAbsent;

float finalMark;

//ask for attendance

cout<<"How many days candidate was absent? ";

//user enters no. of days absent

cin>>intNoDaysAbsent;

if (intNoDaysAbsent<=3)

{

cout<<"Enter candidate's CA marks (out of 100) :";

cin>>intCAMarks;

    if (intCAMarks<0 || intCAMarks>100)

    {

    cout<<"Error: CA marks should be between 0 - 100."<<endl;

    return 0;

    }

    else

        if(intCAMarks<50)

        {

        cout<<"Candidate has not got 50% of the CA marks"<<endl;

        cout<<"Sorry, candidate is not eligible to sit theESE."<<endl;

        return 0;

        }

        else

        cout<<"Candidate is eligible to sit the ESE."<<endl;

}

else{

 

cout<<"Candidate has not attend 80% of the lectures."<<endl;

cout <<"Sorry, candidate is not eligible to sit the ESE."<<endl;

return 0;

}

 

cout<<"Enter candidate's ESE marks (out of 100): ";

cin>>intESEMarks;

 

finalMark = (intESEMarks*(1-fltCARatio) + intCAMarks*fltCARatio) ;

 

if (finalMark>75)

    cout<<"Your Grade is : A"<<endl;

 

else if (finalMark>65)

    cout<<"Your Grade is  :B"<<endl;

 

else if (finalMark>55)

    cout<<"Your Grade is : C"<<endl;

 

else if (finalMark>35)

    cout<<"Your Grade is : S"<<endl;

 

else

    cout<<"Your Grade is : F"<<endl;

return 0;

}