初始化向量 <vector<int> &gt;数据（m，向量 <int> （n））在类矩阵mat（m，n）内

Question

I have to following code:

class matrix{
int m,n;
vector<vector<int>> dat(m,vector<int>n);
matrix(int m, int n){this->m=m;this->n=n;}
}

In order to initialize dat, we must already have m and n. I doubt that this would be happening. The error I'm getting is

'm' is not a type

I cannot seem to figure out how to work around this.

Answer 1

Use the member initializer list :

class matrix
{
    int m,n;
    vector<vector<int>> dat;

public:
    matrix(int m, int n) : m (m), n(n), dat(m, vector<int>(n))
    {
    }
};