Just learning about structs and passing them to functions

[BigNibs]

This is as far as I have gotten. at this point, when I try to fix things, I just make them worse and forget how they were before, I thought it would be best to just ask for some help.

Can you guys please explain what the issues are in a way that makes sense (the compiler errors dont make sense to me)

Any help would be appreciated :)

#include <iostream>
using namespace std;
Dimensions getDimensions();
int calculateArea(int, int);
int calculateParameter(Dimensions);
void showRectangle(const Rectangle &);

struct Dimensions;
{
    int length;
    int width;
};

struct Rectangle
{
    int area;
    int parameter;
    Dimensions sizes;
};


int main()
{
    Rectangle shape;
    shape.sizes = getDimensions();
    
    calculateArea(shape.sizes.length, shape.sizes.width);
    shape.area = lTimesW;
    
    calculateParameter(shape.sizes);
    shape.parameter = addition;
    
    showRectangle(const Rectangle shape)
    
}

Dimensions getDimensions()
{
    Dimensions lAndW;
    cout << "Please enter the length of the shape: ";
    cin >> lAndW.length;
    cout << "Please enter the width of the shape: ";
    cin >> lAndW.width;
    
    return lAndW;
}

int calculateArea(length, width)
{
    int lTimesW = length * width;
    
    return lTimesW;
}

int calculateParameter(sizes)
{
    int addition = 2 * (sizes.length + sizes.width);
    
    return addition;
}

void showRectangle(const Rectangle &rect)
{
    cout << "The area of the rectangle is: " << rect.area << endl;
    cout << "The parameter of the rectangle is: " << rect.parameter;
}

[deleted account xyzzy]

What are the issues you are having, and what are you expecting your program to actually do?

[deleted account xyzzy]

Your function definitions at lines 48 and 55 are missing the data types for the parameters.

int calculateArea(int length, int width)

int calculateParameter(Dimensions sizes)

For a bit of review on function parameters:
https://www.learncpp.com/cpp-tutorial/introduction-to-function-parameters-and-arguments/

[Duthomhas]

You are close. Remember, a struct is like any other thing — you can pass it to a function by value or by reference. Here it suits you to pass the shape by reference and modify it directly.

I have also taken the time to reformat your code a little. Prefer this structure over the antiquated structure you’ve had exampled to you so far.

Notice also how little grief it is to leave out the using namespace.

#include <iostream>

struct Dimensions
{
    int length;
    int width;
};

struct Rectangle
{
    int area;
    int perimeter;
    Dimensions sizes;
};


Dimensions getDimensions()
{
    Dimensions lAndW;
    std::cout << "Please enter the length of the shape: ";
    std::cin >> lAndW.length;
    std::cout << "Please enter the width of the shape: ";
    std::cin >> lAndW.width;
    
    return lAndW;
}


void calculateArea(Rectangle & rect)
{
    rect.area = rect.sizes.length * rect.sizes.width;
}


void calculatePerimeter(Rectangle & rect)
{
    rect.perimeter = 2 * (rect.sizes.length + rect.sizes.width);
}


void showRectangle(const Rectangle & rect)
{
    std::cout << "The area of the rectangle is: "      << rect.area      << "\n";
    std::cout << "The perimeter of the rectangle is: " << rect.perimeter << "\n";
}


int main()
{
    Rectangle shape;
    shape.sizes = getDimensions();
    
    calculateArea(shape);
    calculatePerimeter(shape);
    
    showRectangle(shape);
}

Please enter the length of the shape: 4
Please enter the width of the shape: 3
The area of the rectangle is: 12
The perimeter of the rectangle is: 14

I do not know what utility there is to have the dimensions as a separate structure — I would have just combined it with the Rectangle type, but this should give you good things to look at.

Hope this helps.

[jonnin]

apart from things that do not exist in your sample but may elsewhere:
move the structs to the top. Also dimensions had a stray ; in yours.

you can't say
sometype foo(); //what is this?
and then
struct sometype... //too late, you tried to use it above, where there was no such thing.

there is a way to do that called a forward declaration, but its better if you don't have unnecessary ones (better to rearrange the code if you can).

#include <iostream>
using namespace std;

struct Dimensions
{
    int length;
    int width;
};


struct Rectangle
{
    int area;
    int parameter;
    Dimensions sizes;
};


Dimensions getDimensions();
int calculateArea(int, int);
int calculateParameter(Dimensions);
void showRectangle(const Rectangle &);

[BigNibs]

Oh wow, it makes sense to put the structs above all the functions that use them instead of below- stupid mistake, thanks to everybody on that one. (so thats what the compiler was yelling at me about...)

also @dumthomas using the "namespace std" was the way we were taught since day one of our class. I dont understand the other way- why is it even important if they do the same thing? (just a question)

@George, thanks for the link I will check it out! always good to brush up on the basics! (even though im still learning all the basics XD)


also thank you so much @jonnin and @George and all the others for helping us noobs out, it really makes a huge difference and helps me understand topics better!

[deleted account xyzzy]

Regarding "using namespace std;"....

https://stackoverflow.com/questions/5469060/why-is-std-used-by-experienced-coders-rather-than-using-namespace-std

https://stackoverflow.com/questions/1452721/why-is-using-namespace-std-considered-bad-practice

[BigNibs]

All fixed up now!!

This is exactly the way my teacher wanted it

she was very specific on how things were passed to functions so thats why I did it that way

#include <iostream>
using namespace std;

struct Dimensions
{
    int length;
    int width;
};

struct Rectangle
{
    int area;
    int parameter;
    Dimensions sizes;
};


Dimensions getDimensions();
int calculateArea(int, int);
int calculateParameter(Dimensions);
void showRectangle(const Rectangle &);


int main()
{
    Rectangle shape;
    shape.sizes = getDimensions();
    
    
    shape.area = calculateArea(shape.sizes.length, shape.sizes.width);
    
    shape.parameter = calculateParameter(shape.sizes);
    
    showRectangle(shape);
    
}

Dimensions getDimensions()
{
    Dimensions lAndW;
    cout << "Please enter the length of the shape: ";
    cin >> lAndW.length;
    cout << "Please enter the width of the shape: ";
    cin >> lAndW.width;
    
    return lAndW;
}

int calculateArea(int length, int width)
{
    int lTimesW = length * width;
    
    return lTimesW;
}

int calculateParameter(Dimensions sizes)
{
    int addition = 2 * (sizes.length + sizes.width);
    
    return addition;
}

void showRectangle(const Rectangle &rect)
{
    cout << "The area of the rectangle is: " << rect.area << endl;
    cout << "The parameter of the rectangle is: " << rect.parameter;
}

[mbozzi]

Why is it even important if they do the same thing?

The problem is "A non-unique short name refers to an incorrect entity";
The solution is "Refer to each entity by its unique full name". It's a textbook application of root-cause analysis.

But this is a tiny program, with no third-party code, written by a single programmer, using a distinct naming convention. This software isn't likely to have the problem.

The solution does have a cost, although it is exceedingly small.
Similarly there is a risk of name collisions here, although it is also very small.
There is little to complain about here.