在结构中的数组中的结构中初始化数组时出现问题

Question

I've been tasked to remove some compiler warning. I've been able to boil the problem down to the following example, which I am scratching my head why it won't work. I guess I don't know how to initialize stuff in C++. Any help would be appreciated.

I use g++ like so: g++ init_arr.cpp

Here's the code. I want to initialize all the people at all the tables in Aisle pizza:

// init_arr.cpp
#include <iostream>
#include <string>
#include <sstream>

using namespace std;


struct Person {
    int    id;
    string name;
    double money;
};


struct Table {
    Person tab[4];
};


struct Aisle {
    Table ais[3];
};

int main() {
    cout << "main function()" << endl;

    Aisle pizza =
        {
            {  // Table 0
                { 0, "Tom", 100.0 },
                { 1, "Mary", 101.0 },
                { 2, "Jane", 103.0 },
                { 3, "Joe",  104.0 }
            },

            {  // Table 1
                { 0, "Tom", 100.0 },
                { 1, "Mary", 101.0 },
                { 2, "Jane", 103.0 },
                { 3, "Joe",  104.0 }
            },

            {  // Table 2
                { 0, "Tom", 100.0 },
                { 1, "Mary", 101.0 },
                { 2, "Jane", 103.0 },
                { 3, "Joe",  104.0 }
            }
        };

    return 0;
}

I thought the above would work, but I get the following error:

g++ init_arr.cpp -std=gnu++0x
init_arr.cpp: In function ‘int main()’:
init_arr.cpp:49: error: too many initializers for ‘Table [3]’
init_arr.cpp:49: error: too many initializers for ‘Aisle’

Answer 1

While @us2012 showed what works and provides a good explanation (+1 for him), I find it not very readable. This is an alternative:

Aisle pizza =
    {
        Table {  // Table 0
            Person { 0, "Tom", 100.0 },
            Person { 1, "Mary", 101.0 },
            Person { 2, "Jane", 103.0 },
            Person { 3, "Joe",  104.0 }
        },

        Table {  // Table 1
            Person { 0, "Tom", 100.0 },
            Person { 1, "Mary", 101.0 },
            Person { 2, "Jane", 103.0 },
            Person { 3, "Joe",  104.0 }
        },

        Table {  // Table 2
            Person { 0, "Tom", 100.0 },
            Person { 1, "Mary", 101.0 },
            Person { 2, "Jane", 103.0 },
            Person { 3, "Joe",  104.0 }
        }
    };

Answer 2

You're missing lots of pairs of parentheses. I have added comments to make it clearer which bit starts where.

To put it into one sentence, your problem is that an array with three elements can be initialized with {1,2,3} while a struct that contains an array as its single member is an extra layer and therefore has to be initalized with { {1,2,3} } - the outer layer is the struct , the inner layer is the array.

Aisle pizza =
    { // Aisle init
      { // Table ais[3] init
        {  // ais[0] init
         {  // Person tab[4] init
            { 0, "Tom", 100.0 },
            { 1, "Mary", 101.0 },
            { 2, "Jane", 103.0 },
            { 3, "Joe",  104.0 }
         }
        },

        {  // ais[1] init
         {  // Person tab[4] init
            { 0, "Tom", 100.0 },
            { 1, "Mary", 101.0 },
            { 2, "Jane", 103.0 },
            { 3, "Joe",  104.0 }
         }
        },

        {  // ais[2] init
         {  // Person tab[4] init
            { 0, "Tom", 100.0 },
            { 1, "Mary", 101.0 },
            { 2, "Jane", 103.0 },
            { 3, "Joe",  104.0 }
         }
        }
      }
    };

Answer 3

Each block needs to represent an object. Aisle struct contains an array object (ais). Each element of the ais array contains a Table struct. Each Table struct contains an array object (tab). and so on...

Try this:

    Aisle pizza =
    { // Aisle
        { // .ais
            {  // .ais[0]
                { // .ais[0].tab
                    { 0, "Tom", 100.0 },  // tab[0]
                    { 1, "Mary", 101.0 }, // tab[1]
                    { 2, "Jane", 103.0 }, // tab[2]
                    { 3, "Joe",  104.0 }  // tab[3]
                }
            },

            {  // .ais[1]
                { // .ais[1].tab
                    { 0, "Tom", 100.0 },  // tab[0]
                    { 1, "Mary", 101.0 }, // tab[1]
                    { 2, "Jane", 103.0 }, // tab[2]
                    { 3, "Joe",  104.0 }  // tab[3]
                }
            },

            {  // .ais[2]
                { // .ais[2].tab
                    { 0, "Tom", 100.0 },  // tab[0]
                    { 1, "Mary", 101.0 }, // tab[1]
                    { 2, "Jane", 103.0 }, // tab[2]
                    { 3, "Joe",  104.0 }  // tab[3]
                }
            }

        }
    };