Can't Print array with multiple data types

Question

I created a struct named products that contains multiple data types:

struct products{
    int ID;
    string Name;
    double Price;
    int Quantity;
};

Then in the main function, I created an array named details which utilizes the struct products:

int main(){
    struct products details[5];

Then I gave each array element data.

details[0] = {1, "Apple Juice", 12, 240};
details[1] = {2,"Bread", 10, 100};
details[2] = {3, "Chocolate", 5, 500};
details[3] = {4, "Dates", 50, 150};
details[4] = {5, "Eggs", 30, 360};

finally, I tried to print the values of the element at index 2:

cout<<details[2];

it gave me this error:

"Invalid operands to binary expression ('std::ostream' (aka 'basic_ostream') and 'struct products')"

Here is a picture of the whole code

you get the same error when you try to print a products that is not in an array — 463035818_is_not_an_ai
– 463035818_is_not_an_ai, Commented May 6, 2022 at 11:44
How can the compiler know how to print your struct? You have to define appropriate operator<< yourself. — Quimby
– Quimby, Commented May 6, 2022 at 11:47
Try cout<<details[2].ID and similar constructs for the other things you want to print — L. Scott Johnson
– L. Scott Johnson, Commented May 6, 2022 at 11:48
The array doesn't contain multiple data types - no arrays do. It contains elements of the type products. The array is also completely irrelevant; you would see the same error with products p; std::cout << p; — molbdnilo
– molbdnilo, Commented May 6, 2022 at 12:47

anastaciu · Accepted Answer · 2022-05-06 12:40:42Z

2

There are several ways of doing what you need, here's 3 of them:

Overload << operator:

std::ostream& operator<< (std::ostream& os, const products& pr)
{
    return os << pr.ID << " " << pr.Name << " " << pr.Price << " " << pr.Quantity;
}

std::cout << details[2]; should now work as expected.

Print the struct members directly:

std::cout << details[2].ID << " " << details[2].Name 
    << " " << details[2].Price << " " <<  details[2].Quantity;

Add a to_string() member function:

struct products{
    
//...

    std::string to_string() const
    {
        std::ostringstream os; // #include <sstream>
        os << ID << " " << Name << " " << Price << " " << Quantity;
        return os.str();
    }
};

Usage:

std::cout << details[2].to_string();

edited May 6, 2022 at 12:40

answered May 6, 2022 at 11:58

anastaciu

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Comments

Alex Quchuloria · Accepted Answer · 2022-05-06 12:03:46Z

0

i write you like code.

#include <iostream>
using namespace std;

struct H{
    int n;
    int b;
};

int main() {
    H h[] = {10, 20};
    cout << h[0] << endl; // you can not print it becouse it is array!
    return 0;
}

in this code i try to print struct! but i can not do it!

it like:

#include <iostream>
using namespace std;

struct H{
    int n;
    int b;
};

int main() {
    H h = {10, 20};
    cout << h << endl;
    return 0;
}

just try:

#include <iostream>
using namespace std;

struct H{
    int n;
    int b;
};

int main() {
    H h[] = {10, 20};
    cout << h[0].n << endl;
    cout << h[0].b << endl;
    return

0; }

answered May 6, 2022 at 12:03

Alex Quchuloria

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