Need help with menu program

[namcintosh]

Hello, everyone.

Well, let me cut to the chase and explain my problem.

I am trying to devise a menu plan that uses the if/else if and the while loop. The program calculates the user's weight on a given planet. It first asks for the user's weight, asks them for a choice. If they choose choices 1 though 9, the user's weight will be calculated on whatever choice they picked (for example, if the user inputs 150 as their weight and choose choice #2 for Venus, then the user's weight on Venus would be 135 pounds. However, I am running into some problems.

When I compile the program, the output does not come out as I expect.
The program and the results are listed below:

Program:
// This menu-driven program uses an if/else statement to calculate
// the user's weight on a given planet. It also inserts a loop.

#include <iostream>
#include <iomanip> //Needed for the setprecison command
#include <conio> //Needed to show black output screen
using namespace std;

int main()
{
int choice;
double weight1, weight2;


// Displays the menu choices on the screen.
cout << "\t\tPlanet Menu\n\n";
cout << "1. Mercury\n";
cout << "2. Venus\n";
cout << "3. Earth\n";
cout << "4. Mars\n";
cout << "5. Jupiter\n";
cout << "6. Saturn\n";
cout << "7. Uranus\n";
cout << "8. Neptune\n";
cout << "9. Pluto\n";
cout << "99. Exit\n\n";

cout << "Enter your weight: ";
cin >> weight1;

while (choice !=99)

if (choice == 1)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.40;
cout << "You will weight" << weight2 << "on Mercury." <<endl;
}
else if (choice == 2)
{
cout << "Please make a selection. ";
cin >> choice;
weight2 = weight1 * 0.90;
cout << "You will weight" << weight2 << "on Venus." <<endl;
}
else if (choice == 3)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 1.00;
cout << "You will weight" << weight2 << "on Earth." <<endl;
}
else if (choice == 4)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.40;
cout << "You will weight" << weight2 << "on Mars." <<endl;
}
else if (choice == 5)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 2.50;
cout << "You will weight" << weight2 << "on Jupiter . " <<endl;
}
else if (choice == 6)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 1.10;
cout << "You will weight" << weight2 << "on Saturn." <<endl;
}
else if (choice == 7)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.80;
cout << "You will weight" << weight2 << "on Uranus." <<endl;
}
else if (choice == 8)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 1.2;
cout << "You will weight" << weight2 << "on Neptune. " <<endl;

}
else if (choice == 9)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.01;
cout << "You will weight" << weight2 << "on Pluto. " <<endl;
}
//Outputs the following message when user enters number other
//than 1 through 9 or 99 on the screen.
else if (choice !=99)
{
cout << "The valid choices are 1 through 9 or 99 to exit.\n";
cout << "Run the program again and select one of those.\n";
}

getch();
return 0;
}

Output Line:
Planet Menu

1. Mercury
2. Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus
8. Neptune
9. Pluto
99. Exit

Enter your weight: 150
Please make a selection 2
You will weight60on Mercury.
Please make a selection. 2
You will weight135on Venus.
Please make a selection. 99
You will weight135on Venus.

Do you see the problem? No matter what choice I key in for the first choice, it always calculates for Mercury. Then, when I put that choice in again, it calculates the correct choice. Also, the choice 99 should exit, not do a calculation. (Note: The errors are in bold.) And, when I key in a value that is not one of the choices, instead of just showing "The valid choices are 1 through 9 or 99 to exit. Run the program again and select one of those," all I get is an infinite loop with this statement.
Could there be something wrong with my loops???

[ilikepython]

Hello, everyone.

Well, let me cut to the chase and explain my problem.

I am trying to devise a menu plan that uses the if/else if and the while loop. The program calculates the user's weight on a given planet. It first asks for the user's weight, asks them for a choice. If they choose choices 1 though 9, the user's weight will be calculated on whatever choice they picked (for example, if the user inputs 150 as their weight and choose choice #2 for Venus, then the user's weight on Venus would be 135 pounds. However, I am running into some problems.

When I compile the program, the output does not come out as I expect.
The program and the results are listed below:

Program:
// This menu-driven program uses an if/else statement to calculate
// the user's weight on a given planet. It also inserts a loop.

#include <iostream>
#include <iomanip> //Needed for the setprecison command
#include <conio> //Needed to show black output screen
using namespace std;

int main()
{
int choice;
double weight1, weight2;


// Displays the menu choices on the screen.
cout << "\t\tPlanet Menu\n\n";
cout << "1. Mercury\n";
cout << "2. Venus\n";
cout << "3. Earth\n";
cout << "4. Mars\n";
cout << "5. Jupiter\n";
cout << "6. Saturn\n";
cout << "7. Uranus\n";
cout << "8. Neptune\n";
cout << "9. Pluto\n";
cout << "99. Exit\n\n";

cout << "Enter your weight: ";
cin >> weight1;

while (choice !=99)

if (choice == 1)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.40;
cout << "You will weight" << weight2 << "on Mercury." <<endl;
}
else if (choice == 2)
{
cout << "Please make a selection. ";
cin >> choice;
weight2 = weight1 * 0.90;
cout << "You will weight" << weight2 << "on Venus." <<endl;
}
else if (choice == 3)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 1.00;
cout << "You will weight" << weight2 << "on Earth." <<endl;
}
else if (choice == 4)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.40;
cout << "You will weight" << weight2 << "on Mars." <<endl;
}
else if (choice == 5)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 2.50;
cout << "You will weight" << weight2 << "on Jupiter . " <<endl;
}
else if (choice == 6)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 1.10;
cout << "You will weight" << weight2 << "on Saturn." <<endl;
}
else if (choice == 7)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.80;
cout << "You will weight" << weight2 << "on Uranus." <<endl;
}
else if (choice == 8)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 1.2;
cout << "You will weight" << weight2 << "on Neptune. " <<endl;

}
else if (choice == 9)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.01;
cout << "You will weight" << weight2 << "on Pluto. " <<endl;
}
//Outputs the following message when user enters number other
//than 1 through 9 or 99 on the screen.
else if (choice !=99)
{
cout << "The valid choices are 1 through 9 or 99 to exit.\n";
cout << "Run the program again and select one of those.\n";
}

getch();
return 0;
}

Output Line:
Planet Menu

1. Mercury
2. Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus
8. Neptune
9. Pluto
99. Exit

Enter your weight: 150
Please make a selection 2
You will weight60on Mercury.
Please make a selection. 2
You will weight135on Venus.
Please make a selection. 99
You will weight135on Venus.

Do you see the problem? No matter what choice I key in for the first choice, it always calculates for Mercury. Then, when I put that choice in again, it calculates the correct choice. Also, the choice 99 should exit, not do a calculation. (Note: The errors are in bold.) And, when I key in a value that is not one of the choices, instead of just showing "The valid choices are 1 through 9 or 99 to exit. Run the program again and select one of those," all I get is an infinite loop with this statement.
Could there be something wrong with my loops???

Hello, I don't really see your braces for your while loop. Is that a typo?
Second, the first time you run the loop the program doesn't know what choice is since you ask the user for the values in the if statements. You should ask for choice at the beggining of the loop and then check what is it is with the ifs. Hope that helps.

[namcintosh]

Hello, I don't really see your braces for your while loop. Is that a typo?
Second, the first time you run the loop the program doesn't know what choice is since you ask the user for the values in the if statements. You should ask for choice at the beggining of the loop and then check what is it is with the ifs. Hope that helps.

No, that's not a typo. Where should I put the braces for my while loop? Also, are youu saying that I should ask for the choice after I typed in "Please enter your weight."

[ilikepython]

No, that's not a typo. Where should I put the braces for my while loop? Also, are youu saying that I should ask for the choice after I typed in "Please enter your weight."

Hi, Your braces for the while loop should be one right after the while statement and one after the last if block. That way it will execute until the user enters 99.
Also the "cin >> choice;" line should be at the beginning of the while loop like this:

while (choice != 99)
    {
        cin >> choice;
 
/* calculate weight
    ................. */
    }                       //close while loop
 

Does that help?

[ilikepython]

Oh and also, I'm not exactly sure but there's probably a better way to get the calculated weight depending on the choice instead of all those if statements.

[namcintosh]

Oh and also, I'm not exactly sure but there's probably a better way to get the calculated weight depending on the choice instead of all those if statements.

Well, my homework required that I use the if/else-if loop for this program; it's a new section that I am on.

Also, I tried that, and this is what happened:

cout << "Enter your weight: ";
cin >> weight1;

while (choice !=99)
{
cin >> choice;
}

if (choice == 1)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.40;
cout << "You will weight" << weight2 << "on Mercury." <<endl;
}
Planet Menu

1. Mercury
2. Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus
8. Neptune
9. Pluto
99. Exit

Enter your weight: 185
9

What am I doing wrong.

[ilikepython]

Well, my homework required that I use the if/else-if loop for this program; it's a new section that I am on.

Also, I tried that, and this is what happened:

cout << "Enter your weight: ";
cin >> weight1;

while (choice !=99)
{
cin >> choice;
}

if (choice == 1)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.40;
cout << "You will weight" << weight2 << "on Mercury." <<endl;
}
Planet Menu

1. Mercury
2. Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus
8. Neptune
9. Pluto
99. Exit

Enter your weight: 185
9

What am I doing wrong.

You put the closing while brace after the "cin" line. That i means it will repaetedly ask for choice until you enter 99. You don't want that. Try putting it at the end of all the calculations so the it can loop correctly like this:

while (choice is not 99)
    {                                         // begin brace
        ask for choice
        calculate weight here
    }                                           // end brace after everything is done
 

so once it reaches the end brace it "loops" back up to the begin brace.

Does that clarify things?

[namcintosh]

You put the closing while brace after the "cin" line. That i means it will repaetedly ask for choice until you enter 99. You don't want that. Try putting it at the end of all the calculations so the it can loop correctly like this:

while (choice is not 99)
    {                                         // begin brace
        ask for choice
        calculate weight here
    }                                           // end brace after everything is done
 

so once it reaches the end brace it "loops" back up to the begin brace.

Does that clarify things?

Pardon me, if I seem like a dummy; but I am really new at this.
Can you please insert in the program where exactly does that statement go???
Here is the program again:
cout << "Enter your weight: ";
cin >> weight1;

while (choice !=99)
{
cin >> choice;
}

if (choice == 1)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.40;
cout << "You will weight" << weight2 << "on Mercury." <<endl;
}
else if (choice == 2)
{
cout << "Please make a selection. ";
cin >> choice;
weight2 = weight1 * 0.90;
cout << "You will weight" << weight2 << "on Venus." <<endl;
}
else if (choice == 3)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 1.00;
cout << "You will weight" << weight2 << "on Earth." <<endl;
}
else if (choice == 4)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.40;
cout << "You will weight" << weight2 << "on Mars." <<endl;
}
else if (choice == 5)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 2.50;
cout << "You will weight" << weight2 << "on Jupiter . " <<endl;
}
else if (choice == 6)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 1.10;
cout << "You will weight" << weight2 << "on Saturn." <<endl;
}
else if (choice == 7)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.80;
cout << "You will weight" << weight2 << "on Uranus." <<endl;
}
else if (choice == 8)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 1.2;
cout << "You will weight" << weight2 << "on Neptune. " <<endl;

}
else if (choice == 9)
{
cout << "Please make a selection ";
cin >> choice;
weight2 = weight1 * 0.01;
cout << "You will weight" << weight2 << "on Pluto. " <<endl;
}
//Outputs the following message when user enters number other
//than 1 through 9 or 99 on the screen.
else if (choice !=99)
{
cout << "The valid choices are 1 through 9 or 99 to exit.\n";
cout << "Run the program again and select one of those.\n";
}

getch();
return 0;
}

[ilikepython]

Pardon me, if I seem like a dummy; but I am really new at this.
Can you please insert in the program where exactly does that statement go???
Here is the program again:

 cout << "Enter your weight: ";
    cin  >> weight1;
 
                while (choice !=99)
                {
                   cin >> choice;
 
                if (choice == 1)
        {
        cout << "Please make a selection ";
        cin  >> choice;
        weight2 = weight1 * 0.40;
        cout << "You will weight" << weight2 << "on Mercury." <<endl;
                  }
                else if (choice == 2)
        {
        cout << "Please make a selection. ";
        cin  >> choice;
        weight2 = weight1 * 0.90;
        cout << "You will weight" << weight2 << "on Venus." <<endl;
                  }
                else if (choice == 3)
        {
        cout << "Please make a selection ";
        cin  >> choice;
        weight2 = weight1 * 1.00;
                cout << "You will weight" << weight2 << "on Earth." <<endl;
        }
                else if (choice == 4)
        {
        cout << "Please make a selection ";
        cin  >> choice;
        weight2 = weight1 * 0.40;
        cout << "You will weight" << weight2 << "on Mars." <<endl;
        }
                else if (choice == 5)
        {
        cout <<  "Please make a selection ";
        cin  >> choice;
        weight2 = weight1 * 2.50;
                cout << "You will weight" << weight2  << "on Jupiter . " <<endl;
                }
                else if (choice == 6)
        {
        cout << "Please make a selection ";
        cin  >> choice;
        weight2 = weight1 * 1.10;
                cout << "You will weight" << weight2 << "on Saturn." <<endl;
                }
                else if (choice == 7)
        {
        cout << "Please make a selection ";
        cin  >> choice;
        weight2 = weight1 * 0.80;
                cout << "You will weight" << weight2 << "on Uranus." <<endl;
                  }
                else if (choice == 8)
        {
        cout << "Please make a selection ";
        cin  >> choice;
        weight2 = weight1 * 1.2;
                cout << "You will weight" << weight2 << "on Neptune. " <<endl;
 
                  }
                else if (choice == 9)
        {
        cout << "Please make a selection ";
        cin  >> choice;
        weight2 = weight1 * 0.01;
                cout << "You will weight" << weight2 << "on Pluto. "  <<endl;
                }
                //Outputs the following message when user enters number other
                //than 1 through 9 or 99 on the screen.
            else if (choice !=99)
                {
                cout << "The valid choices are 1 through 9 or 99 to exit.\n";
                cout << "Run the program again and select one of those.\n";
                }
                }
        getch();
    return 0;
}
 

That's Ok.
I edited it. Notice the position of the while braces: they're in bold.
If you need more help just ask.

[namcintosh]

That's Ok.
I edited it. Notice the position of the while braces: they're in bold.
If you need more help just ask.

Well, I got half of the problem right, thanks to you. :-)

However, I am still running into a problem.
Here is my output:
Output 1
Planet Menu

1. Mercury
2. Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus
8. Neptune
9. Pluto
99. Exit

Enter your weight: 185
5
Please make a selection 5
You will weight462.5on Jupiter .
6
Please make a selection 6
You will weight203.5on Saturn.

As you see, it first asks me for my weight. Because I have the cin >> choice line, it waits for me to enter a choice. then, once I enter a choice, it then asks me to make a selection. But, when I deleted the cin >> choice, this is the problem that I ran into:

Output 2:
Planet Menu

1. Mercury
2. Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus
8. Neptune
9. Pluto
99. Exit

Enter your weight: 185
Please make a selection 1
You will weight74on Mercury.
Please make a selection 2
You will weight74on Mercury.
Please make a selection. 2
You will weight166.5on Venus.
Please make a selection. 99
You will weight166.5on Venus.

Also, when I enter an invalid amout, it shows the infinite loop again. What do I do. The first input is right (it makes the right calculations and executes correctly), but how can I make it stop asking the user for the choice twice and make it ask for it once instead. Do you have C++ on your computer? Maybe you can copy and paste the program and you will see what I mean.

Thanks!!!