Thread: First Program (Calculator)

Originally Posted by robatino

Edit: Actually, you NEED to replace the while statements, since as it is, the appropriate case would be executed over and over in an infinite loop.

Thus the "return 0;" at the end of each

Originally Posted by brewbuck

Thus the "return 0;" at the end of each

I realized that before seeing your post, and removed my edit. But the whiles should still go, just because it's weird to use while instead of if when it's only going to execute at most once.

Originally Posted by robatino

Basically, looks good. You should replace the 4 while statements with either if-else statements, or better yet, a switch statement with 4 cases. Also, the last 2 lines in each of the 4 cases are the same, so the only thing you need to do conditionally is assign a value to result.

I haven't run into the switch statement yet in my studies, what is the basic syntax of that?

Thanks for the comments guys.

Alright , so does that look better.

Ok, I think I finally got it, thanks a bunch.

are you sure your first program wasnt

Code:

#include <iostream>
using namespace std;
int main()
{
	cout << "Hello World.";
return 0;
}

2 remarks -
1. use more meaningful variable names that explain what they contain. Eg, ("first_number, second_number, operator_choice" would be more understandable than "x, y, z"). For a small program like this it probably doesn't matter, but if you plan to write larger programs later on, might as well make it a habit now (you wouldn't want to be tracking down what xaayz mean in a 10000 lines program, right?)
2. consider adding a do...while loop before the switch that prompts the user until he/she enters a valid input. Something like this:

Code:

int operator_choice = 0;
do {
    cout << "(1) Add \n";
    cout << "(2) Subtract \n";
    cout << "(3) Multiply \n";
    cout << "(4) Divide \n";
    cin >> operator_choice;
} while ((operator_choice > 4) || (operator_choice < 1));

But even so, that loop will fail horribly to due the mechanics of cin.
Either you need to a) read a string and validate or b) clear in the input buffer if something went wrong.

stand corrected. I was only thinking about invalid input as in a number greater than 4 or less than 1.

To the OP: What Elysia meant is that if the input is not even a number, the loop I suggested would fail.

Originally Posted by cyberfish

2 remarks -
1. use more meaningful variable names that explain what they contain. Eg, ("first_number, second_number, operator_choice" would be more understandable than "x, y, z"). For a small program like this it probably doesn't matter, but if you plan to write larger programs later on, might as well make it a habit now (you wouldn't want to be tracking down what xaayz mean in a 10000 lines program, right?)
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I have to disagree here. In this particular case, where one performs basic arithmetic on just two variables, x and y are perfectly understandable. I would almost go sofar as to say that they are the most logical choice, given that many math texts use x and y, or x1 and x2, for bivariate functions.