Problems with if and conditions

Question

I’m making a code that receives three values and orders them from the highest to the lowest. As a condition, when the numbers are repeated, an error message is displayed and the program must close. If the numbers are distinct, it skips this if and proceed to the actual ordination. I used the following line of code:

if (z==x or y==z or x==y)
    cout << "\nErro. Os valores devem ser diferentes. Tente novamente: \n" << endl;
  //restante do código

However, even if the numbers are different, the program always displays the message

"Error. Values should be different. Try again:"

I would like it to be displayed only when there was the error, and in this case, the program should end right there, and not continue, because this is also occurring.

Below follows the complete code:

#include <iostream>

using namespace std;

int x,y,z,ft,sd,th;

int main()
{
    cout << "Digite 3 valores reais e diferenteees: \n";
    cin >> x;
    cin >> y;
    cin >> z;

    if (z==y or x==z or x==y)
        cout << "\nErro. Os valores devem ser diferentes de 0 e nao repetidos. Tente novamente: \n" << endl;

    if (x>y and x>z)
        ft=x;
        else if (x>y and x<z)
            sd=x;
            else if (x>z and x<y)
            sd=x;
                else if (x<y and x<z)
                    th=x;

    if (y>x and y>z)
        ft=y;
        else if (y<x and y>z)
            sd=y;
            else if (y<z and y>x)
                sd=y;
                else if (y<x and y<z)
                th=y;

    if (z>x and z>y)
        ft=z;
        else if (z<x and z>y)
            sd=z;
            else if (z<y and z>x)
                sd=z;
                else if (z<x and z<y)
                    th=z;

    cout << "\nOs valores ordenados sao: \n" << endl;
    cout << "Valor mais alto: " << ft<< endl;
    cout << "Valor intermediario: " << sd<< endl;
    cout << "Valor mais baixo: " << th<< endl;

    return 0;
}

Answer 1

I reformulated his program to solve the problem and give an organized to make it more readable. I recommend paying close attention to the changes.

I’m not sure if your code is doing what you want but I did some tests with some values and seems to give consistent results and solves the main problem you were complaining about. I organized the indentation and put the declaration of variables inside the function since there is no reason for them to be outside.

Variables must be declared in the most internal possible scope, in this case it is the function. The way it was, the variables would work as "global" variables, which isn’t usually a good idea. Of course in this restricted case does not cause any problem but in more complex codes cause. So you are already learning the right.

I made a change by placing a loop for the code to repeat if the entered data is not according to the need. This way of using a continue conditional and a break unconditional is not ideal but did not want to modify its logic, as you are learning you might have difficulty understanding. Basically this code inside the block while will run once and leave because of the break. Unless he goes into if, there the continue on it will make the break be skipped, and will repeat the loop until no longer enter the if.

#include <iostream>
using namespace std;

int main() {
    int x, y, z, ft, sd, th;
    while(true) {
        cout << "Digite 3 valores reais e diferentes: \n";
        cin >> x;
        cin >> y;
        cin >> z;

        if (z == y || x == z || x == y) {
            cout << "\nErro. Os valores devem ser diferentes de 0 e nao repetidos. Tente novamente: \n" << endl;
            continue;
        }
        break;
    }
    if (x > y && x > z)
        ft = x;
    else if (x > y && x < z)
        sd = x;
    else if (x > z && x < y)
        sd = x;
    else if (x < y && x < z)
        th = x;

    if (y > x && y > z)
        ft = y;
    else if (y < x && y > z)
        sd = y;
    else if (y < z && y > x)
        sd = y;
    else if (y < x && y < z)
        th = y;

    if (z > x && z > y)
        ft = z;
    else if (z < x && z > y)
        sd = z;
    else if (z < y && z > x)
        sd = z;
    else if (z < x && z < y)
        th = z;

    cout << "\nOs valores ordenados sao: \n" << endl;
    cout << "Valor mais alto: " << ft<< endl;
    cout << "Valor intermediario: " << sd<< endl;
    cout << "Valor mais baixo: " << th<< endl;
}

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

Note that in the ideone I put keys in ifs. They are not necessary in this case but it is advisable to always use to avoid confusion when you need.

Answer 2

If you include these two lines before the 'main' statement, your code will compile without errors:

#define or ||
#define and &&