How to access the members of a dynamic array of structures with pointers?

Question

This is the main structure:

#include <iostream>
using namespace std;

struct CandyBar 
{
    char brand_name[30];
    float candy_weight;
    int candy_calories;
};

int main()
{
    CandyBar * snack = new CandyBar [3];

    return 0;
}

I managed to initialize the dynamically allocated 3 structures in an array of 3 elements. I tried to access the structures via:

snack[0]->brand_name = "Whatever";

with no result, even with the other method:

(*snack[0]).brand_name = "Whatever";

I really have no clue, since I have been studying these for a couple of days.

Error: expression must be a modifiable lvalue

User567845
– User567845

2012-09-28 01:30:32 +00:00
Commented Sep 28, 2012 at 1:30 — User567845
– User567845, Commented Sep 28, 2012 at 1:30

nneonneo · Accepted Answer · 2012-09-28 01:38:14Z

2

Since snack is an array of structures, just use snack[0].brand_name.

You also can't copy a string just by using = in C. Use strcpy instead:

strcpy(snack[0].brand_name, "Kitkat");

edited Sep 28, 2012 at 1:38

answered Sep 28, 2012 at 1:20

nneonneo

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2 Comments

User567845 Over a year ago

I discovered that assigning with = is illegal with membership operators, while legal in general i.e. char words[20] = { "Lots of words"}; Venturing into the esoteric corners of the language, thanks.

nneonneo Over a year ago

Actually, it's only legal when initializing char[] arrays (or when it is treated as char *).

Barmar · Accepted Answer · 2012-09-28 01:38:17Z

0

In C++, strings are arrays, and arrays cannot be copied using =. Try:

strcpy(snack[0].brand_name, "Whatever");

answered Sep 28, 2012 at 1:38

Barmar

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3 Comments

User567845 Over a year ago

Thanks for the input, I had completely ignored I could include <cstring>

Luc Danton Over a year ago

Should be 'string literals are arrays'.

User567845 Over a year ago

You both answered at the same time, so I've accepted nneonneo's final answer because he answered the very first time, sorry.

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