adjusting based off age.

[Matthew Shoppas]

Hey I hope this is the right place, I'm taking C++ for my first programming class in college and I have a problem that I need to solve. I am writing a function for finding jacket size and I need to add 1/8 inch for every 10 years starting at age 30. Every 10 years you need to add another 1/8 inch so from 30-39 its 1/8 from 40-49 its 1/4 and so on. How would I write this in the function? Thanks!

[ciphermagi]

Well, take their age, subtract 30, then subtract modulo 10, then divide by 10, then multiply by 1/8 inch and add that number to the jacket size.

[Matthew Shoppas]

I'm sorry, but modulo 10? Ha I am sorry if I am being slow, but what does that mean? I think I get what you're saying but not that final piece.

[Stewbond]

We're missing some information, You didn't define what size they were at age 30. I'm assuming we don't want to extrapolate from age 0/size0.

double get_size(int age)
{
    const double size_at_30 = 60; // Change this;
    return ((age-30.)/80.) + size_at_30;
}

[ciphermagi]

subtract modulo 10

means to subtract from whatever value you have the remainder of division by 10, or in other words, round down to the closest 10:

int x = 17; // x = 17
cout << x % 10; // Output: 7
cout << x - (x % 10); // Output: 10
cout << (x - (x % 10)) / 10 // Output: 1 

[Matthew Shoppas]

Their size is a variable being inputed by the user. What I have right now is:
{

int height, age, weight;
double hat_size, jacket_size, waist_in_inches;

cout<<"Enter your height: "<<endl;
cin>>height;
cout<<"Enter your age: "<<endl;
cin>>age;
cout<<"Enter your weight: "<<endl;
cin>>weight;
hat_size=hat_function(weight, height);
cout<<"Your hat size is: "<<hat_size<<endl;

return 0;
}

double hat_function(double weight_in_lbs, double height_inches)
{
double hat_multiple=2.9, hat_size;
hat_size=(weight_in_lbs/height_inches)*hat_multiple;
return hat_size;
}

double jacket_function(double weight, double height)
{

}

[Matthew Shoppas]

sorry I didn't put my code in the nice box xD

[ciphermagi]

Starting size is irrelevant. Even if it's 0, then you'll start off with 1/8 inch, because you're adding to the value.

[Matthew Shoppas]

I GET IT! so i put that in a if-else statement saying: if (age >= 30)
{
((age-(age%10))/10)*(1/8)
}

so if they were 34 it would be
34-4=30
30/10=3
3*1/8= 3/8
there is my addition.
YOU GUYS ROCK!!
ciphermagi thank you so much!

[ciphermagi]

You forgot the part where you subtract 30. in order to start at 30, instead of starting at 0...