c - Cで構造体の動的な長さの2D配列を参照で渡す

Question

1. 次のような警告が表示されます:「互換性のないポインター型から 'arraySumLoc' の引数 1 を渡しています」
2. 関数 arraySumLoc() を介して得られた結果は不適切であり、理由を理解できません。
3. 配列の宣言中に malloc() を使用したい場合、どのような変更が必要ですか。

---

#include<stdio.h>
#include<conio.h>

typedef struct item {
    double cost;
    double commission;
} item;

typedef struct loc {
    int x;
    int y;
} loc;

double arraySumLoc(struct item *arr, loc fromLoc, loc toLoc) {

    double sumOfCost = 0.0;
    int fromX, fromY, toX, toY, indexX, indexY;

    if (fromLoc.x > toLoc.x) {
        fromX = toLoc.x;
        toX = fromLoc.x;
    } else {
        fromX = fromLoc.x;
        toX = toLoc.x;
    }

    if (fromLoc.y > toLoc.y) {
        fromY = toLoc.y;
        toY = fromLoc.y;
    } else {
        fromY = fromLoc.y;
        toY = toLoc.y;
    }

    for(indexX = fromX; indexX <= toX; indexX++) {
        for (indexY = fromY; indexY <= toY; indexY++) {
            sumOfCost += ((struct item*)(arr+indexX))[indexY].cost;
        }
    }
    return sumOfCost;
}

int main() {

    int i, j, row, col;

    printf("Enter number of row: ");
    scanf("%d", &row);
    printf("Enter number of Column: ");
    scanf("%d", &col);

    struct item product[row][col];

    for(i = 0; i < row; i++) {
        for(j = 0; j < col; j++) {
            scanf("%lf", &product[i][j].cost);
        }
    }

    loc fromLoc, toLoc;
    fromLoc.x = 0;
    fromLoc.y = 0;
    toLoc.x = row - 1;
    toLoc.y = col - 1;

    printf("\n\nSum of cost : %.2lf", arraySumLoc((struct item**)(&product), fromLoc, toLoc));
    getch();

    return 0;
}

Answer 1

double arraySumLoc(struct item **arr, loc fromLoc, loc toLoc) {

double sumOfCost = 0.0;     
int fromX, fromY, toX, toY, indexX, indexY;

if (fromLoc.x > toLoc.x) {
    fromX = toLoc.x;
    toX = fromLoc.x;
} else {
    fromX = fromLoc.x;
    toX = toLoc.x;
}

if (fromLoc.y > toLoc.y) {
    fromY = toLoc.y;
    toY = fromLoc.y;
} else {
    fromY = fromLoc.y;
    toY = toLoc.y;
}

for(indexX = fromX + 1; indexX <= toX; indexX++) {
    for (indexY = fromY + 1; indexY <= toY; indexY++) {
        sumOfCost += (((struct item*)arr+indexX))[indexY].cost;
    }
}
return sumOfCost;

} printf("\n\nコストの合計: %.2f", arraySumLoc((struct item**)(&product), fromLoc, toLoc));