Try, Catch, And Throw

[A_StClaire_]

it's been frustrating rearranging these things in the code below and
never getting the result I want.

I'm looking for the system to cout a single "Invalid choice. Try
again:" in response to every incorrect entry the user gives, regardless
of whether the invalid entry is a single character or 20 characters.

can anyone help?

void Game::RunSinglePlayerGame()
{
bool quit = false;

while(quit == false)
{
RunSinglePlayerSequence();
Interface::Instance().ClearScreen();

int choice;
bool validChoice = false;

cout << "\n\n Play again?\n\n 1. Yes\n 2. No\n\n ";

while(validChoice == false)
{
cin >> choice;

switch(choice)
{
case 1:
validChoice = true;
break;
case 2:
validChoice = true;
quit = true;
cout << "\n\n\n\n Thanks for playing!\n\n ";
break;
default:
cout << "\n Invalid choice. Try again: ";
break;
}

}

}

}

[Zara]

On 3 Dec 2005 01:48:00 -0800, A_*********@hotmail.com wrote:

it's been frustrating rearranging these things in the code below and
never getting the result I want.

I'm looking for the system to cout a single "Invalid choice. Try
again:" in response to every incorrect entry the user gives, regardless
of whether the invalid entry is a single character or 20 characters.

can anyone help?

void Game::RunSinglePlayerGame()
{
bool quit = false;

while(quit == false)
{
RunSinglePlayerSequence();
Interface::Instance().ClearScreen();

int choice;
bool validChoice = false;

cout << "\n\n Play again?\n\n 1. Yes\n 2. No\n\n ";

while(validChoice == false)
{
cin >> choice;

You must detect when the input is not a valid number
if (cin.fail())
{
choice=0;
}

switch(choice)
{
case 1:
validChoice = true;
break;
case 2:
validChoice = true;
quit = true;
cout << "\n\n\n\n Thanks for playing!\n\n ";
break;
default:
cout << "\n Invalid choice. Try again: ";
break;
}

}

}

}

[A_StClaire_]

Zara wrote:

You must detect when the input is not a valid number
if (cin.fail())
{
choice=0;
}

added your code after cin >> choice but it does not appear to have any
impact.

[John Carson]

<A_*********@hotmail.com> wrote in message
news:11**********************@g49g2000cwa.googlegr oups.com

Zara wrote:

You must detect when the input is not a valid number
if (cin.fail())
{
choice=0;
}

added your code after cin >> choice but it does not appear to have any
impact.

You need to reset cin to a valid state and clear its buffer. After

cin>>choice;

add

if (cin.fail())
{
choice=0;
cin.clear(cin.rdstate()&~std::ios::failbit); // set to valid state
cin.ignore(numeric_limits<int>::max(), '\n'); // empty buffer
}

You will need to

#include <limits>

to get numeric_limits<int>::max().
--
John Carson

[Alf P. Steinbach]

* A_*********@hotmail.com:

it's been frustrating rearranging these things in the code below and
never getting the result I want.

I'm looking for the system to cout a single "Invalid choice. Try
again:" in response to every incorrect entry the user gives, regardless
of whether the invalid entry is a single character or 20 characters.

can anyone help?
Does the title of this posting, "Try, Catch, And Throw", mean that you
have enabled exceptions in the input stream?

void Game::RunSinglePlayerGame()
{
bool quit = false;

while(quit == false)
{
RunSinglePlayerSequence();
Interface::Instance().ClearScreen();

int choice;
Make choice a std::string.

bool validChoice = false;

cout << "\n\n Play again?\n\n 1. Yes\n 2. No\n\n ";

while(validChoice == false)
{
cin >> choice;
cin.clear();
std::getline( cin, choice );

switch(choice)
Replace 'switch' with if-else construction.

{
case 1:
validChoice = true;
break;
case 2:
validChoice = true;
quit = true;
cout << "\n\n\n\n Thanks for playing!\n\n ";
break;
default:
cout << "\n Invalid choice. Try again: ";
break;
}

}

}

}

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[A_StClaire_]

got it. thx all. I guess exceptions are not appropriate for this type
of situation.

[Matteo]

> switch(choice)

{
case 1:
validChoice = true;

I think you want
case '1':
here instead of
case 1:

What you have refers to (probably) ASCII code 1, which can't really be
typed in. Use single quotes when refering to character constants.

-matt

[John Carson]

"Matteo" <ma****@ncsa.uiuc.edu> wrote in message
news:11**********************@g47g2000cwa.googlegr oups.com

switch(choice)
{
case 1:
validChoice = true;

I think you want
case '1':
here instead of
case 1:

What you have refers to (probably) ASCII code 1, which can't really be
typed in. Use single quotes when refering to character constants.

Not true. The variable choice is defined to be an integer. Thus when 1 is
typed in

cin >> choice;

assigns the value 1 to choice.

--
John Carson

[Matteo]

Whoops! I don't know why I thought he was reading into a char. That'll
teach me to read the OP's code more careflly next time.

Sorry,
-matt