Question

我想在C ++中阅读以下文件。

000001011100110
100000010101100
001001001001100
110110000000011
000000010110011
011000110101110
111010011011110
011001010010000

我知道文件中有多少rows和columns。我想阅读每个integer并将其存储在2-D matrix的整数中。这里的每个整数表示0是一个条目，1是另一个条目。因此，在上面的示例中，有15 0和1 s。

Answer 1

int main () {
  string line;
  ifstream myfile ("example.txt");
  if (myfile.is_open())
  {
    while ( getline (myfile,line) )
    {
      cout << line << endl;
      int lineNumber;
      stringstream(line) >> lineNumber;
      //Do smith with this line read amount of digits
      int tempNumber = lineNumber;
      num_digits = 0;
      //get number of digits
      while(tempNumber > 0) {
         num_digits++;
         tempNumber/=10;
      }
      //print digits
      std::stringstream tmp_stream;
      tmp_stream << tempNumber;
      for (i = 0; i < tmp_stream.str().size(); i++)
      {
          std::cout << "Digit [" << i << "] is: " << tmp_stream.str().at(i) << std::endl;
      }
    }
    myfile.close();
  }

  else cout << "Unable to open file"; 

  return 0;
}

//获取位数是一些额外的，也许你会找到一个更好的获取数字的方法，所以这可能是有用的

完全符合您的目的，只需要这样做：

if (myfile.is_open()){
    int line = 0;
    while ( getline (myfile,line) )
        {
          cout << line << endl;
          for (i = 0; i < line.size(); i++)
          {
              std::cout << "Digit [" << i << "] is: " << line.at(i) << std::endl;
              int lineDigitNumber;
              stringstream(line) >> lineDigitNumber;
          }
    line++;

    //Fill array with line and i
    }
    myfile.close();
}

Answer 2

#include <iostream>
#include <fstream>
#include <string>
#include <vector>

using namespace std;

const size_t NROWS = /* number of rows */;
const size_t NCOLS = /* number of cols */;

int main () {
  vector<vector<int> > myvec (NROWS, vector<int>(NCOLS));
  ifstream myfile ("example.txt");
  if (myfile.is_open ())
    {
      string line;
      for (size_t rowcount = 0; rowcount < NROWS && getline (myfile, line);
       ++rowcount)
    {
      size_t colcount = 0;
      for (string::const_iterator it = line.begin ();
           it != line.end () && colcount < NCOLS; ++it, ++colcount)
        {
          myvec[rowcount][colcount] = *it - '0';
        }
    }
      myfile.close ();
    }

  else
    cerr << "Unable to open file" << endl;

  return 0;
}

关于std::vector<T>的一个巧妙的事情是构造函数(size_t, T& default_value = T())都预分配和分配。因此，使用它制作多维数组非常容易 - 只需根据需要嵌套向量，并为第二个参数嵌套(n-1)级别。

Answer 3

这是我使用quick'n'dirty矩阵类实现的“练习”;）

#include <iostream>
#include <fstream>
#include <stdexcept>
#include <string>

class CMatrix {

public:

    CMatrix(unsigned int r, unsigned int c)
    : rows(r), cols(c), a(new int [r*c])
    {}

    // copy constructor and copy assignment operator come here

    ~CMatrix()
    {
        delete [] a;
    }

    int& at(unsigned int r, unsigned int c)
    {
        if (r >= rows || c >= cols) throw std::out_of_range("Out of range access");
        return a[r*cols + c];
    }

private:

    unsigned int rows;
    unsigned int cols;
    int* a;

};


int main()
{
    // assuming the sample file OP provided
    const unsigned int n_rows = 8;
    const unsigned int n_cols = 15;

    std::ifstream myfile("in.txt");

    if (!myfile.is_open()) {
        // report error
    } else {

        CMatrix matrix(n_rows, n_cols);
        std::string line;
        unsigned int m = 0;
        unsigned int n = 0;

        while (getline(myfile, line))
        {
            n = 0;
            for (char& c : line) {
                matrix.at(m,n) = c == '0' ? 0 : 1;
                ++n;
            }
            ++m;
        }
    }
}

用C ++读取具有整数的文件

3 个答案: