CODEWITHSUNDEEP
c++arraysvisual-c++c++11
rasul1719435
rasul1719435

Reputation: 115

how to create an function thats returns an array

I would like to know how to prototype a function that returns a array which also takes in an array. after prototyping the array how can i implement it

is this correct?

coffee* getData(*coffe);

int main() {
    coffee cf[256];
    coffee FinalCoffee[256];
    FinalCoffee=getData(cf);
}

coffee getData(coffee objcf[]) {
    for(int i=0;i<SIZE;i++) {
        objcf[i].brand="nescafe";
    }
    return coffee;
}

Plsease do advice me on this. i need to be able to get back array so that i can pass the updated array to another function to process it.

Upvotes: 1

Views: 169

Answers (3)

Leonid Volnitsky
Leonid Volnitsky

Reputation: 9144

You can do this in C++. References to the rescue. Ugly syntax ahead, typedefs are recommended:

#include <iostream>
using namespace std;

template<size_t N>
int (&f(int(&A)[N])) [N] {
        for(auto& i: A) i +=10;
        return A; 
} 

int main() {
        int A[3] = {1,2,3};
        auto& AA = f(A);
        for(auto i: AA)   cout << i << "\n";
}

But as, Konrad Rudolph noted, you actually do not need return anything from f(), your array is modified in place. And your function can be much simpler:
void f(int (&A)[N])

Upvotes: 4

Konrad Rudolph
Konrad Rudolph

Reputation: 545913

Your code doesn’t even have matching declaration and function definition. This doesn’t work.

But the following does:

std::vector<coffee> getData(std::vector<coffee> const& objs) {
    std::vector<coffee> result;
    // Do something to fill result
    return result;
}

But if, as in your example, you want to manipulate the original array, rather than returning a new one, then it makes more sense to not have a return value at all, and to pass the argument as a non-const reference:

void manipulateData(std::vector<coffee>& objs) {
    for (auto& obj : objs)
        obj.brand = "nescafe";
}

As a rule of thumb, try to avoid C arrays in favour of C++ standard library containers. This will make your life much, much easier.

Upvotes: 5

Some programmer dude
Some programmer dude

Reputation: 409364

To start with, the declaration (prototype) and the definition (implementation) of the function headers are different:

coffee* getData(*coffe);

Versus

coffee getData(coffee objcf[])

The last one doesn't even return a pointer.

As for your question, your prototype says that getData returns a pointer but you assign it to an array. This will not work. Instead declare FinalCoffee as a pointer:

coffee cf[256];
coffee* FinalCoffee;
FinalCoffee=getData(cf);

However you don't really need that. When getData modifies the array you pass as argument, then those modifications will be in the cf array too as arrays are passed as references.

Upvotes: 2

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