Request for member '' in '', which is of non-class type

Question

I am trying to loop through a struct array and initialize its member "history", an int array, to 0 (Undoubtedly, you'll have a better suggestion than the one-value-at-a-time loop, which will be welcome, but that's not what the question is about).

I get an error not only I do not understand, but I cannot see how the multiple internet posts about it come into a function within my case.

The error is:

In function 'int main()':....
|error: request for member 'history' in 'coin', which is of non-class type 'coin_t [10]'|

This is my code (true copy-paste from a new project):

#include <iostream>
using namespace std;

// Hand input parameters
const int coinCount=10;
int weight[coinCount]={11,11,9,10,10,10,10,10,10,10};
const int maxDepth=6;
const int caseCount=360;

// GLOBALS
struct coin_t
{
    float w;
    int history[maxDepth];
    int curDepth;
};

coin_t coin[coinCount];

int main()
{
    int i,j;

    //Initialize coin struct array
    for(i=0;i<coinCount;i++)
    {
        coin[i].w=weight[i];
        coin[i].curDepth=-1;
        for(j=0;j<maxDepth;j++) coin.history[j]=0; // Here's the error
    }
}

Answer 1

coin is an array of struct coin_t with sized coinCount. You need to access by operator[] for the corresponding element in the array.

coin[i].history[j] = 0;
//  ^^^

If you want to zero-initialize the history you could do better

struct coin_t
{
    float w;
    int history[maxDepth]{0};
    //                   ^^^^
    int curDepth;
};

by which you can skip the extra looping

    for (j = 0; j < maxDepth; j++)
        coin[j].history[j] = 0;

---

That being said C++ offers better std::array. Consider use if its suitable to the case.