Thread: Math function code - couple probs, tips?

This code allows the user to pick a math function (trig funtions, log, ln), set an x range, and it displays the x,y values of the funtion in that range.

I have three problems:

typing "4" doesn't make it exit < - fixed
typing anything other than a number makes the program go wacky
even with the if statement in the switch-case function, making the minimum range less than 0 STILL does not warn the user, if they have a log function selected. <-fixed

I'd also like some tips, pointers, anything, to make it smaller and more efficient.

Code:

// The purpose is to take an x range and then display all the values of certain mathematical functions within that range.
// Demonstrates use of switch-case statemsnts, while statemsnts, and basic classes.



#include <iostream.h>
#include <stdlib.h>
#include <math.h>

void DrawTable(int,int,int);

int main()
{
      bool exit = false;
      bool exit2 = false;
      int opt;
      int opt2;
      int function = 1;
      int max = 10;
      int min = -10;

      cout << "************************************************************\n";
      cout << "**********************MATH FUNCTIONS************************\n";
      cout << "************************************************************\n";
      while(exit == false)
      {
             cout << "Please make a selection\n";

             cout << "1. Select the function\n";
             cout << "2. Set the x range\n";
             cout << "3. Display the value table\n";
             cout << "4. Exit\n";
             cin >> opt;

             switch(opt)
             {
                        case(1): while(exit2 == false)
                                 {
                                 cout << "\nSelect one of these functions: " << endl;
                                 cout << "1. sine\n";
                                 cout << "2. cosine\n";
                                 cout << "3. tangent\n";
                                 cout << "4. log (base 10)\n";
                                 cout << "5. natural log (base e)\n";
                                 cin >> opt2;
                                 switch(opt2)
                                 {
                                             case(1): function = 1;
                                                      exit2 = true;
                                                      break;
                                             case(2): function = 2;
                                                      exit2 = true;
                                                      break;
                                             case(3): function = 3;
                                                      exit2 = true;
                                                      break;
                                             case(4): function = 4;
                                                      exit2 = true;
                                                      break;
                                             case(5): function = 5;
                                                      exit2 = true;
                                                      break;
                                             default: cout << "Please select again\n\n";
                                                      break;
                                 }
                                 }
                                 break;


                        case(2): for(;;)
                                 {
                                 cout << "What should the minimum x value be?\n";
                                 cin >> min;
                                 cout << "\nWhat should the maximum x value be?\n";
                                 cin >> max;
                                 if ( ( min > max ) || ( ( min <= 0 ) && ( function = ( 4 || 5 ) ) ) )
                                            {
                                             cout << "The minimum cannot be greater than the max, or you have chosen values less than 0 for a logarithmic function!\n";
                                             continue;
                                            }
                                 else break;
                                 }
                                 break;

                        case(3): DrawTable(min, max, function);
                                 break;
                        case(4): exit = true;
                                 break;
                        default: cout << "Please make another selection\n";
                                 break;
                }
      }
      system("PAUSE");
      return 0;
}

void DrawTable(int mi, int ma, int func)
{
     switch(func)
     {
                 case(1): cout << "\nX\t|\tY\n";
                          cout << "\t|\n";
                          for(mi;mi<=ma; mi++)
                          {
                                        cout << mi << "\t|\t" << sin(mi) << endl;
                          }
                          break;
                 case(2): cout << "\nX\t|\tY\n";
                          cout << "\t|\n";
                          for(mi;mi<=ma; mi++)
                          {
                                        cout << mi << "\t|\t" << cos(mi) << endl;
                          }
                          break;
                 case(3): cout << "\nX\t|\tY\n";
                          cout << "\t|\n";
                          for(mi;mi<=ma; mi++)
                          {
                                        cout << mi << "\t|\t" << tan(mi) << endl;
                          }
                          break;
                 case(4): cout << "\nX\t|\tY\n";
                          cout << "\t|\n";
                          for(mi;mi<=ma; mi++)
                          {
                                        cout << mi << "\t|\t" << log10(mi) << endl;
                          }
                          break;
                 case(5): cout << "\nX\t|\tY\n";
                          cout << "\t|\n";
                          for(mi;mi<=ma; mi++)
                          {
                                        cout << mi << "\t|\t" << log(mi) << endl;
                          }
                          break;
                 default: cout << "ERROR!\n";
       }
       return;
}

This is like.. the 2nd program I've written since starting reading a book (and I'm 300 pages in the book). I thought it'd be time to apply some stuff :I know (although I would have liked to use classes, pointers, and references in there somewheres)

Thanks for any help.