Can't clear memory used.

Hi all,

The program can't clear the memory space after user entered a invalid choice. It works fine for numeric 0 - 9 but if i enter an alphabet, the text 'invalid choice' will be displayed twice (IE: after showing the error message, it'll show again in "Enter Choice: ", hence preventing user from entering a choice).

Code:

---

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

// To pause the screen for user to read.
void pause(void)
{
        getchar();
}

void main(void)
{

        int choice;

        do
        {
                system("cls");

                cout << "=========================" << endl;
                cout << "1.) Contacts" << endl;
                cout << "2.) Messaging" << endl;
                cout << "3.) Make Call" << endl;
                cout << "4.) Call Log" << endl;
                cout << "5.) Accessories" << endl;
                cout << "6.) Tools" << endl;
                cout << "7.) Off Mobile" << endl;
                cout << "=========================" << endl;
               
                cout << "Please select a menu: ";
                cin >> choice;

                switch (choice)
                {
                        case 1 : contacts();
                                break;
                        case 2 : cout << "go to messaging" << endl;
                                pause();
                                break;
                        case 3 : cout << "go to make call" << endl;
                                pause();
                                break;
                        case 4 : cout << "go to call log" << endl;
                                pause();
                                break;
                        case 5 : accessories();
                                break;
                        case 6 : tools();
                                break;
                        case 7 : // prints quit msg.
                                break;

                        default:
                                cout << "Invalid Choice!" << endl;
                                pause();
                                break;
                }
               
        } while (choice!=7);
          cout << "Program terminating..." << endl;
}

---

I can't find where the error lies... hope someone can help me out.

PS: There are other functions in this program which I didn't paste it out because it's not revelant to the error that's occuring.

Thanks :)

Get rid of void main before a mod catches you using it. :D

The program goes into an error state if a char is entered into an int variable.

cin.clear(1);
cin.ignore(80, '\n');

Since you're using digits for you choices, just use a char variable and

switch(char variable)
{
case '1': ....

..//

}

Quote:

---

Get rid of void main before a mod catches you using it. :D

---

Eh, hehe, i don't really understand what you mean by this? You mean void main should not appear in any codes i pasted?

Anyway, i'm not sure about the cin.clear(1);

Hmm, i'll give it a try and let you know.

Thanks :)

Heh... it's late and I'm sleepy. I don't use this namespace stuff normally, but I decided to play with it here. For you purists, if it's wrong, then it's because I don't use it :D

Try this. Hopefully it will work.

Code:

---

#include <iostream>

using namespace std;

int main(void)
{
  int try1;
   
  static char MENU[] = "=========================\n"
                      "1.) Contacts\n"
                      "2.) Messaging\n"
                      "3.) Make Call\n"
                      "4.) Call Log\n"
                      "5.) Accessories\n"
                      "6.) Tools\n"
                      "7.) Off Mobile\n"
                      "========================\n";
                               
  do
  {
    std::cout << endl << MENU;
    std::cin >> try1;
   
    if(std::cin.fail()) // int variable try an alpha char
    {
            std::cin.clear();
            std::cin.ignore(80, '\n'); // clean up the junk
    }
   
    switch(try1)
    {
        case 1  : std::cout << "Contacts" << endl;
                  break;
       
        case 3  : std::cout << "Make Call" << endl;
                  break;
        case 999: break;
        default : std::cout << try1 << " is invalid.";
                  break;
    }
  }while(try1 != 999);           
 
       
  return EXIT_SUCCESS;
}

---

void main() is not a good thing to do. Search the board for why not. :)

once you are "using namespace std" you don't have to put it at the start of each cout etc, it's redundant - and afaik u don't need the (void) after main either - just make it "int main()"
but otherwise looks good :)

I'm not sure about namespace since I never came across it or use it before.

ronin I solved it using cin.ignore where I change the variable of type int to char and added the cin.ignore line just after pause(); in default case.

Anyway, thanks for all the help guys :)