c++ - 插入 vector 并调整 vector 的大小

Question

如何调整包含整数值的 vector 的大小。

std::vector<std::vecotr<int>> MyVector;
int value = 10;

//need to insert values as 2 rows and 3 columns, like
//Myvector[0][0] = value;
//Myvector[0][1] = value;
//Myvector[0][2] = value;
//Myvector[1][0] = value;
//Myvector[1][1] = value;
//Myvector[1][2] = value;

// ......
//here i have to resize the vector size to 4 rows and 5 cols using resize() function.

MyVector.resize(.......); //Hoe is this possible.

第一个问题是，我必须插入 2 行 3 列的值。为此，我如何使用 push_back 函数。之后需要调整到指定的大小。因为它是 vector 的 vector ，所以我对此感到担心。

Answer 1

您可以将 vector 的 vector 想象成一个矩阵，其中成员 vector 是“行”。

int main()
{
    std::vector<std::vector<int> > MyVector;
    //Create a row:
    std::vector<int> subVector;
    subVector.push_back(1);
    subVector.push_back(2);
    //put the row into the vector:
    MyVector.push_back(subVector);
    //create another row:
    subVector.clear();
    subVector.push_back(3);
    subVector.push_back(4);
    //put the second row into the vector
    MyVector.push_back(subVector);
    //access the first row and add an element to it:
    MyVector[0].push_back(6);
    //access the second row and add an element to it:
    MyVector[1].push_back(6);
}