A small issue with a switch menu in c++

[chrome0011]

Ok, doing my homework here, and everything seems right, except for this small issue... when my code is done executing, it should return to the menu. It does this, but it seems to think an invalid choice has been made and it looks like this:

http://img256.imageshack.us/img256/7351/codeqs1.png

here's the code...

 

[chrome0011]

 

[chrome0011]

 

[squirtle24]

I suspect this might be the problem:
"cin >> infixString" combined with "cin.getline(buffer, MAX)" later on.

You choose option 1 at the menu and enter your expression. "cin >> infixString" gets the expression, but not the newline character, which remains in the input buffer.

Later, you use getline to get the next input (the menu choice); getline, by default, reads until it encounters a newline (which is still the first character in the input buffer), so your buffer remains empty.

You can get past this by using getline to get infixString, or placing a cin.ignore() after cin >> infixString (not very robust, though).

 

[chrome0011]

You were right!! I used this fix:

int getValidNonNegInt(char * prompt)
{
const int MAX = 80;
char buffer[MAX];
int i;
cout << prompt;
fflush(stdin); //The one small change.
cin.getline(buffer, MAX);
.......
}

Thanks for helping out!