[英]storing a 2D array into a 2D vector in c++
Suppose I have a following 2D matrix in the following format.假设我有以下格式的二维矩阵。 First line indicates the dimension and the rest other lines contains the elements.第一行表示维度,其余行包含元素。 In this case it's a 6*6 Matrix:在这种情况下,它是一个 6*6 矩阵:
6
1 2 3 4 2 3
3 3 4 5 2 1
4 3 3 1 2 3
5 4 3 6 2 1
3 2 4 3 4 3
2 3 4 1 5 6
Normally we can store the matrix in a vector using this:通常我们可以使用以下方法将矩阵存储在向量中:
typedef std::vector<int32_t> vec_1d;
typedef std::vector<vec_1d> vec_2d;
vec_2d array{
{ 1, 2, 3, 4, 2, 3 }
, { 3, 3, 4, 5, 2, 1 }
, { 4, 3, 3, 1, 2, 3 }
, { 5, 4, 3, 6, 2, 1 }
, { 3, 2, 4, 3, 4, 3 }
, { 2, 3, 4, 1, 5, 6 }
};
But if I want to take this array in the format I have shown above from a text file into a 2d vector like the above one, how will I do this in c++ ?但是,如果我想将上面显示的格式的这个数组从文本文件转换为像上面那样的二维向量,我将如何在 c++ 中做到这一点?
This should work:这应该有效:
#include "fstream"
#include "vector"
using namespace std;
int main()
{
ifstream fin("file.txt");
int n;
fin >> n;
vector < vector <int> > matrix (n, vector <int>(n));
// or vec_2d matrix (n, vec_1d(n)); with your typedefs
for (auto &i: matrix)
for (auto &j: i)
fin >> j;
}
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