While loop not breaking?? C-CodePudding

I'm trying to construct a simple dice game in C . I do not understand why it's not breaking out of the while loop.

You are supposed to ONLY be able to bet 100, 300, or 500€.

Even if I enter my bet "100-300-500" which is supposed to be correct. It still loops and says it's an invalid bet. Why doesn't it progress to the if statement when I have if ((bet1 == 100) || (bet1 ==300) || (bet1==500))

I've tried putting the if statement before the while loop and all sorts of things. I can't get it to work.

cout << "Please place a bet. 100, 300, 500kr" << endl;
cin >> bet1;

while ((bet1 <= 99) || (bet1 >= 101) || (bet1 <= 299) || (bet1 >= 301) || (bet1 <= 499) || (bet1 >= 501)) {
    cout << "Please place a valid bet" << endl;
    cin >> bet1;
}
if ((bet1 == 100) || (bet1 ==300) || (bet1==500)) {
    cout << "You have deposited " << " " << bet1 << "" << "And you now have: "<< saldo - bet1 << " " << "Remaining on your account." << endl;
}

CodePudding user response：

This loop

while ((bet1 <= 99) || (bet1 >= 101) || (bet1 <= 299) || (bet1 >= 301) || (bet1 <= 499) || (bet1 >= 501)) {
    cout << "Please place a valid bet" << endl;
    cin >> bet1;
}

is an infinite loop for any valid entered value 100, 300 or 500.

For example if the user will enter 100 then at least this condition (bet1 <= 299) evaluates to true. If the user will enter 300 then at least this condition (bet1 >= 101) evaluates to true. If the user will enter 500 then at least again this condition (bet1 >= 101) evaluates to true.

You should rewrite the while loop for example like

while ( bet1 != 100 && bet1 != 300 && bet1 != 500 )  {
    cout << "Please place a valid bet" << endl;
    cin >> bet1;
}

Using your approach to writing the loop the condition can look like

while ( ( bet1 <= 99 ) || ( bet1 >= 101 && bet1 <= 299 ) || (bet1 >= 301 && bet1 <= 499 ) || ( bet1 >= 501 ) ) {
    cout << "Please place a valid bet" << endl;
    cin >> bet1;
}

CodePudding user response：

Any finite integer value is either >=101 or <=299. Oring more conditions does not change that the condition is always true.

If you want to loop until bet1 is either 100,300 or 500:

while ( bet1 != 100 && bet1 != 300 && bet1 != 500) {...

CodePudding user response：

Imagine the following: Someone enters 100. Now the while-loop checks: <=99? no. >>Or<< maybe >=101? nope. >>Or<< <=299? It is! Therefore, the condition is true and it asks for a valid bet.

See how you can work it out from here.

CodePudding user response：

Just this will always be true: (bet1 >= 101) || (bet1 <= 299)

ALL numbers on the number line are either >= 101 or <= 299

You need to use the logical AND (&&) operator e.g ((bet1 >= 101) && (bet1 <= 299)) || ((bet1 >= 301) && (bet1 <= 499))

CodePudding user response：

Your condition in the while loop is always true. You can check the valid number(s) in the following way:

while (bet1 != 100 && bet1 != 300 && bet1 != 500)
{
    cout << "Please place a valid bet" << endl;
    cin >> bet1;
}