/* Using if statements */
#include <iostream>
using namespace std;
 
int main()
{
    int grade;
 
    cout << "Enter a grade and I will tell you if you passed: ";
    cin >> grade;
 
    if (grade > 60)
        cout << "Passed" << endl;
 
    return 0;
}

/* Using if/else statements */
#include <iostream>
using namespace std;
 
int main()
{
    int num1;
    cout << "Enter an integer, and I will tell you ";
    cout << "if the number is positive: ";
    cin >> num1;  // read an integer
 
    if (num1 > 0)
        cout << num1 << " is positive. "<< endl;
    else
        cout << num1 << " is not positive. "<< endl;
 
    return 0;
}

/* Using nested if/else statements */
#include <iostream>
using namespace std;
 
int main()
{
    int grade;
    cout << "Enter a numerical grade, and I will tell you" << endl;
    cout << "how well the student performed: ";
    cin >> grade;    // read an integer
 
    cout << "The student received a letter grade of ";
    if (grade >= 90 )
        cout << "A";
    else if (grade >= 80)
        cout << "B";
    else if (grade >= 70)
        cout << "C";
    else if (grade >= 60)
        cout << "D";
    else
        cout << "F";
    cout << "." << endl;
 
    return 0;
}

/* Using logical operators to validate input */
#include <iostream>
using namespace std;
 
int main()
{
    int grade;
    cout << "Enter a numerical grade, and I will tell you" << endl;
    cout << "how well the student performed: ";
    cin >> grade;    // read an integer
 
    if (grade >= 0 && grade <= 100)
    {
        cout << "The student received a letter grade of ";
        if (grade >= 90 )
            cout << "A";
        else if (grade >= 80)
            cout << "B";
        else if (grade >= 70)
            cout << "C";
        else if (grade >= 60)
            cout << "D";
        else
            cout << "F";
        cout << "." << endl;
    }
    else
        cout << "The grade must be between 0 and 100." << endl;
 
    return 0;
}