我该如何解决这个问题

using namespace std;
//a class that will handle all the calculations requested by user
class MathOperations{
  public:
    void Message();
    int setSum(int,int);
    int setSuB(int,int);
    int setMul(int,int);
    float setDiv(float,float *);
    int setSqrt(int);
};
//Implementation:
void MathOperations:: Message(){
    cout<< " Welcome. This program simulates a calculator "<<endl;
}
// implementing the setters methods.
int MathOperations::setSum(int a, int b){
    int total;
    total = a + b;
    return total;
} 
int MathOperations:: setSuB(int a, int b){
    int total;
    total = a - b;
    return total;
}
int MathOperations:: setMul(int a, int b){
    int total;
    total = a * b;
    return total;
}
float MathOperations:: setDiv(float a, float *b){
    float result;
    if(b ==0){
        cout << "Using the Default Value of 1 because you can't devide by 0"<<endl;
    }
    else
        result = (a / *b);
    return result;
}
int MathOperations::setSqrt(int Square){
    int total;
    total = sqrt(Square);
    return total;
}
int main(int argc, const char * argv[])
{
    //creating instances of class MathOperations
    MathOperations add, sub, mul, div, sqrt;
    ///creating variable to hold user input
    int fnum;
    float snum;
    char opt= '0';
    //propt user for values
    cout << " Enter a Number"<<endl;
    cin >> fnum;
    cout << " Enter a second number " <<endl;
    cin >> snum;
    float total = div.setDiv(fnum, &snum);
    cout << total <<endl;

    cout << " What would you like to do '+','-','*','/' ?"<<endl;
    cin >> opt;
    switch (opt) {
      case '+' :
        {
            int total = add.setSum(fnum, snum);
            cout << " The Total Sum of both numbers is " << total <<endl;
        }
        break;
      case '-' :
        {
            int total = sub.setSuB(fnum, snum);
            cout << " The Subtraction of both Numbers is " << total << endl;
        }
        break;
      case '*' :
        {
            int total = mul.setMul(fnum, snum);
            cout << " The Multiplication of both Numbers is " << total << endl;
        }
        break;
      case '/' :
        {
            int total = div.setDiv(fnum, &snum);
            cout << " The Division of both Numbers is " << total <<endl;
        }
      default:
        cout << " Not a valid Option"<<endl;
    }
}

该部门无法正常工作。我在这里做错了什么？我正在尝试创建一个包含数学运算的类。我是一个初学者，试图在这里做一些练习。你能告诉我我具体做错了什么吗？