Please help... Avoiding run-time errors.

Heya,

I created this code ->

int max_point;

do
{
//code...
cin>>max_point;
} while(max_point < 1 || max_point > 100)

As long as the user inputs a number, this works well.
However, when a user enters a character, the appl. crashes.

What may I do to fix this?

Rgrds,
Marc

Just check the input stream, if its bad then exit the program, break the loop or whatever. I think this should work

Code:

---

int max_point;

do
{
//code...
cin>>max_point;

  if( !cin.good( ) )
  {
      cout << "Incorrect input\nExiting program...." << endl;
      exit( 1 );
  }
} while(max_point < 1 || max_point > 100)

---

Try this:

Code:

---

int max_point;

do
{
//code...
cin>>max_point;
if (cin.fail())
{
  cin.clear();
  cin.ignore();
}
} while(max_point < 1 || max_point > 100);

---

Or this:

Code:

---

int max_point;

do
{
//code...
cin>>max_point;
if (cin.fail())
{
  cin.clear();
  cin.seekg(0);
}
} while(max_point < 1 || max_point > 100);

---

Thanks for your answers!
Here is the code I tried:

Code:

---

        do
        {
                system("CLS");
                cout<<"\n\n\t[[ Scissors, Paper, Stone 2002 ]] - [ Coded by mvb ]";
                cout<<"\n\n\t[ N E W    G A M E ]";
                cout<<"\n\n\tPOINTS DETAILS:";
                cout<<"\n\n\tPoints for a win [ between 1 and 100 ]...";
                cout<<"\n\n\t\t>> ";
                cin>>pointwin;
                if (cin.fail())
                {
                  cin.clear();
                  cin.ignore();
                }
        } while (pointwin < 1 || pointwin > 100 );
        do
        {
                system("CLS");
                cout<<"\n\n\t[[ Scissors, Paper, Stone 2002 ]] - [ Coded by mvb ]";
                cout<<"\n\n\t[ N E W    G A M E ]";
                cout<<"\n\n\tPOINTS DETAILS:";
                cout<<"\n\n\tPoints for a win [ between 1 and 100 ]...";
                cout<<"\n\t\t>> "<<pointwin;
                cout<<"\n\n\tPoints for a draw [ between 0 and 100 ]...";
                cout<<"\n\n\t\t>> ";
                cin>>pointdraw;
                if (cin.fail())
                {
                  cin.clear();
                  cin.ignore();
                }
        } while (pointdraw < 0 || pointdraw > 100 );
        do
        {
                system("CLS");
                cout<<"\n\n\t[[ Scissors, Paper, Stone 2002 ]] - [ Coded by mvb ]";
                cout<<"\n\n\t[ N E W    G A M E ]";
                cout<<"\n\n\tPOINTS DETAILS:";
                cout<<"\n\n\tPoints for a win [ between 1 and 100 ]...";
                cout<<"\n\t\t>> "<<pointwin;
                cout<<"\n\n\tPoints for a draw [ between 0 and 100 ]...";
                cout<<"\n\t\t>> "<<pointdraw;
                cout<<"\n\n\tPoints for a loss [ between 0 and 100 ]...";
                cout<<"\n\n\t\t>> ";
                cin>>pointloss;
                if (cin.fail())
                {
                  cin.clear();
                  cin.ignore();
                }
        } while (pointloss < 0 || pointloss > 100 );

---

If I enter a letter in the first prompt, it works fine (it asks me again).
However, when I input a letter in the second, it simply fills it with a 0 and moves on to the third and final input.

What might be wrong in this case?

Thanks,
Marc

Try this:

Code:

---

for(int i=3; i>0; i--;)
{
do
        {
                system("CLS");
                cout<<"\n\n\t[[ Scissors, Paper, Stone 2002 ]] - [ Coded by mvb ]";
                cout<<"\n\n\t[ N E W    G A M E ]";
                cout<<"\n\n\tPOINTS DETAILS:";
                cout<<"\n\n\tPoints for a win [ between 1 and 100 ]...";
                cout<<"\n\n\t\t>> ";
                cin>>pointwin;
                if (cin.fail())
                {
                  cin.clear();
                  cin.ignore();
                                  i++;
                                  //so it "reasks"
                }
        } while (pointwin < 1 || pointwin > 100 );
}

---

Thanks, it worked :D

A question though, why is there need to do that? Shouldn't it work well without the for loop?

Rgrds,
Marc :D

Well you should do it anyways. Less code. Why not do it?

Anytime the cin fails, nothing gets stored for the variable, so whatever value it held previously it still holds. You can fix this either with a fail flag, or initializing the variable prior to the loop. Either:

Code:

---

        pointdraw = -1;
        do
        {
                system("CLS");
                cout<<"\n\n\t[[ Scissors, Paper, Stone 2002 ]] - [ Coded by mvb ]";
                cout<<"\n\n\t[ N E W    G A M E ]";
                cout<<"\n\n\tPOINTS DETAILS:";
                cout<<"\n\n\tPoints for a win [ between 1 and 100 ]...";
                cout<<"\n\t\t>> "<<pointwin;
                cout<<"\n\n\tPoints for a draw [ between 0 and 100 ]...";
                cout<<"\n\n\t\t>> ";
                cin>>pointdraw;
                if (cin.fail())
                {
                  cin.clear();
                  cin.ignore();
                }
        } while (pointdraw < 0 || pointdraw > 100 );

---

Or something like:

Code:

---

        bool fail = false;
        do
        {
                system("CLS");
                cout<<"\n\n\t[[ Scissors, Paper, Stone 2002 ]] - [ Coded by mvb ]";
                cout<<"\n\n\t[ N E W    G A M E ]";
                cout<<"\n\n\tPOINTS DETAILS:";
                cout<<"\n\n\tPoints for a win [ between 1 and 100 ]...";
                cout<<"\n\t\t>> "<<pointwin;
                cout<<"\n\n\tPoints for a draw [ between 0 and 100 ]...";
                cout<<"\n\n\t\t>> ";
                cin>>pointdraw;
                if (cin.fail())
                {
                  cin.clear();
                  cin.ignore();
                  fail = true;
                }
        } while (fail == true || pointdraw < 0 || pointdraw > 100);

---

Thanks :D