Can I use a range of values with switch/case statements using if/else?

Since I can't use ranges in switch case, and since the cin input for (grade) comes before this function. Is it possible to use if else statements to automatically input the grade for the user into the switch statement? so they don't have to input their grade twice.. for example

cin >> grade;

if (grade>=90 && grade<=100)
{
    grade == A
}

switch(grade){
case 'A':
    {
        cout << "Your Grade is an A" << endl;
        break;
    }

instead of

case '80-89':
    {
        cout << "Your Grade is B" << endl;
        break;
    }