C++ compile time error: expected identifier before numeric constant

Solution 1:

You cannot do this:

vector<string> name(5); //error in these 2 lines
vector<int> val(5,0);

in a class outside of a method.

You can initialize the data members at the point of declaration, but not with () brackets:

class Foo {
    vector<string> name = vector<string>(5);
    vector<int> val{vector<int>(5,0)};
};

Before C++11, you need to declare them first, then initialize them e.g in a contructor

class Foo {
    vector<string> name;
    vector<int> val;
 public:
  Foo() : name(5), val(5,0) {}
};

Solution 2:

Initializations with (...) in the class body is not allowed. Use {..} or = .... Unfortunately since the respective constructor is explicit and vector has an initializer list constructor, you need a functional cast to call the wanted constructor

vector<string> name = decltype(name)(5);
vector<int> val = decltype(val)(5,0);

As an alternative you can use constructor initializer lists

 Attribute():name(5), val(5, 0) {}