CODEWITHSUNDEEP
c#
beyonder
beyonder

Reputation: 1

BMI & BMR calculator

I'm trying to create a method that takes a user's height, weight, and age, and returns their BMI and BMR.

I think I've done this fine.

However, the last thing I need to do is add some validation to make sure the user has put in some sensible numbers. The constraints being applied to the input are:

50 [cm] ≤ height ≤ 220 [cm]
10 [kg] ≤ weight ≤ 250 [kg]
18 [years] ≤ age ≤ 70 [years]

To do this, I've tried using if statements

if (getHight >= 220 && getHight <= 50)
{
    Console.WriteLine("Unfortunately, your input is incorrect, please try again");
}
else if (getAge >= 70 && getAge <= 18)
{
    Console.WriteLine("Unfortunately, your input is incorrect, please try again");
}
else if (getWeight >= 250 && getWeight <= 10)
{
    Console.WriteLine("Unfortunately, your input is incorrect, please try again");
}

However, regardless of what I ender, nothing shows up in the console by way of validation errors. It just outputs my BMI and BMR.

What am I missing here?

Upvotes: 0

Views: 252

Answers (2)

YungDeiza
YungDeiza

Reputation: 4608

Your mistake is that you are using AND instead of OR.

You cannot both be taller than 220cm and shorter than 50cm.

Use OR operators instead of AND:

if (getHight > 220 || getHight < 50)
{
    Console.WriteLine("Unfortunately, your input is incorrect, please try again");
}
else if (getAge > 70 || getAge < 18)
{
    Console.WriteLine("Unfortunately, your input is incorrect, please try again");
}
else if (getWeight > 250 || getWeight < 10)
{
    Console.WriteLine("Unfortunately, your input is incorrect, please try again");
}

Also as @PaulF mentioned, you should not be using <= and >= since the valid range of values is inclusive. Since your logic is the inverse (invalid values), you should drop the = and just use < and >.

Upvotes: 4

Rufus L
Rufus L

Reputation: 37070

As already mentioned, you should be using || instead of && when doing the comparisons and you should be using < and > since the boundary values are acceptable. You might spend some time reading up on the Boolean logical operators - AND, OR, NOT, XOR so they all make sense, because they're very common and used in just about every program you'll write.

I just wanted to add another possible solution in case you're doing a lot of these types of comparisons, which is to write an extension method for them. This way you only have to write it once, which reduces the chance of error.

Below I have an extension method that tests if a number is between a minimum and maximum value (along with an option to specify if those boundary values as valid). Note that I assumed you're testing with an int type, but you can change the type easily by changing the this int value to this double value or this float value, or whatever numeric type you're using:

public static class Extensions
{
    public static bool IsBetween(this int value, int min, int max, 
        bool inclusive = true)
    {
        return inclusive ?
            min <= value && value <= max:
            min < value && value < max;
    }
}

Now if you include that class in your project, we can use this method to test if the value is not between our accepted values by using the ! not operator. Also note that I changed the else if to separate if statements. This way, if there's more than one error, they all get reported at the same time and the user can correct them all at once. I also changed the error message so the user actually knows what's wrong and how to fix it:

// In your program class, not in the Extensions class above

if (!getHeight.IsBetween(50, 220))
{
    Console.WriteLine("ERROR: Height must be an integer between 50 and 220");
}

if (!getAge.IsBetween(18, 70))
{
    Console.WriteLine("ERROR: Age must be an integer between 18 and 70");
}

if (!getWeight.IsBetween(10, 250))
{
    Console.WriteLine("ERROR: Weight must be an integer between 10 and 250");
}

Upvotes: 0

Related Questions