Question

I have defined two structs

class foo() {
public:
    struct spatialEntry {
        bool block;
        CoherenceState_t state;
    };

    struct accumulationEntry {
        uint64_t offset;
        std::vector<spatialEntry> pattern;
    };

    std::vector<int> v;
    std::list<accumulationEntry> accumulationTable;

    foo() {
        v.resize(16);
    }
};

Now I want to initialize the size of std::vector<spatialEntry> to 16 like v. How can I do that?

Answer 1

Just define a constructor for the class which contains that member and then resize() as:

class foo() {
public:
   //...
   struct accumulationEntry 
   {
       uint64_t offset;
       std::vector<spatialEntry> pattern;
       accumulationEntry()
       {
            pattern.resize(16);  //<--------- this is what you want?
       }
    };
    std::vector<int> v;
    std::list< accumulationEntry > accumulationTable;
    foo()
    {
       v.resize(16);
    }
};

But then if you use resize, then it is better to do that as :

       accumulationEntry() : pattern(16)  //<--- note this
       {
            //pattern.resize(16);
       }

That is, use member-initialization list. Do the same for foo also.