我如何将一个文件流到一个矩阵中的C ++ boost ublas？ [英] How do I stream a file into a matrix in C++ boost ublas?

问题描述

我想读取一个包含矩阵数据的文件到boost矩阵中。 已经被假定为这种事情的运算符重载，我可以让它写一个标准流（cout）。我不知道对方走什么错了。我对C ++相当新，所以我猜我对文件流做了一个不正确的假设，但它似乎是有意义的。以下是我要进行的网页：

I'm trying to read in a file that contains matrix data into a boost matrix. "" is already supposed to have operator overloads for this sort of thing and I can get it to write to a standard stream (cout). I don't know what's wrong with going the other way. I'm fairly new to C++, so I'm guessing I'm making an incorrect assumption regarding file streams, but it seemed like it made sense. Here are the web pages I'm going on:

http://www.boost.org/doc/libs/1_51_0/boost/numeric/ublas/io.hpp

http://www.cplusplus.com/reference/iostream / ifstream / ifstream /

这是我的代码：

using namespace std;
matrix<double> M;
ifstream s("C:\temp\perm.txt", ifstream::in);

s >> M;
s.close();

std::cout << M;

这是我的档案：

[4,4]((0,0,1,0),(0,0,0,1),(0,1,0,0),(1,0,0,0))

推荐答案

，请尝试一下，看看会发生什么。如果这不工作，我怀疑问题是文件路径错误或程序未能从文本文件读取：

Here is a small example, please try it out and see what happens. If this doesn't work, I suspect that the problem is that the file path is wrong or the program is failing to read from the text file:

#include <boost/numeric/ublas/io.hpp>
#include <boost/numeric/ublas/matrix.hpp>
#include <iostream>
#include <fstream>

int main()
{
    boost::numeric::ublas::matrix<double> m;
    std::ifstream s("C:\temp\perm.txt");
    if (!s)
    {
        std::cout << "Failed to open file" << std::endl;
        return 1;
    }
    if (!s >> m)
    {
        std::cout << "Failed to write to matrix" << std::endl;
        return 1;
    }
    std::cout << "Printing matrix: ";
    std::cout << m;
}

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