How can I pass the whole struct to a function including all elements?

Question

I have a structure that I want to pass to a function which will sort the struct. However, I don't know how to pass the WHOLE structure.

What I've done is this until now:

void sort_datoteka_sifra(pole &artikli){
}

And I call it like sort_datoteka_sifra(artikli[0]) etc.. but it only passes the [0] elements, I want to pass the whole structure, so that I can use it in the function without having to call artikli[0], artikli[1] and so on in the main function.

Answer 1

You have several options here.

1. Pass the array as a pointer to its first element as well as the number of elements:

    void sort_datoteka_sifra(pole *artikli, int count){ } 

   If count is static (known at compile time), you can also pass the array by reference:

    void sort_datoteka_sifra(pole (&artikli)[100]){ } 

   If you don't want to hardcode the count, use a function template:

    template <int N> void sort_datoteka_sifra(pole (&artikli)[N]){ } 

2. Use std::vector instead of C-arrays:

    void sort_datoteka_sifra(std::vector<pole> &artikli){ } 

3. Use std::sort instead of your custom sort function ( #include <algorithms> ) and use it with either your existing C-array or (recommended) a std::vector :

    std::sort(std::begin(artikli), std::end(artikli)); 

   You have to provide a way to compare two objects; this is done by either overloading operator< or by passing a function (or functor) to the sort algorithm:

    bool comparePole(const pole & a, const pole & b) { return /* condition when you want to have a before b */ } std::sort(std::begin(artikli), std::end(artikli), &comparePole); 

   If you don't want to write a function and have C++11, you can use a lambda function:

    std::sort(std::begin(artikli), std::end(artikli), [](const pole & a, const pole & b) { return /* condition when you want to have a before b */ }); 

   If you want to compare the elements by some member (which has a corresponding operator< overload, which is the case for simple types like int , std::string , etc.), use compareByMember from my other answer at https://stackoverflow.com/a/20616119/592323 , eg let's say pole has an int ID by which you want to sort:

    std::sort(std::begin(artikli), std::end(artikli), compareByMember(&pole::ID)); 

   To sort a sub-array of size count , don't use std::end but:

    std::sort(std::begin(artikli), std::begin(artikli) + count, &comparePole); 

Of course you can combine the third option with one of the first two, ie provide a sort function which is implemented in terms of std::sort .

Answer 2

Your function requests a reference to a single element. And you obviously also pass only a single element. So, to pass the complete array, you should use a pointer, if it's an array allocated with new Or a statically allocated array, eg

void fun(pole* artikli);

Otherwise for C++, it's common to use std::vector and pass it by reference:

std::vector<pole> artikli;

void fun(std::vector<pole>& artikli);