c++ - 遍历文件直到 *string* 然后读取列直到 *no decimal*

Question

我有一个文件看起来像

some header
this is the first block
                         1    2    3    4
                         5    6    7    8
                         9   10   11   12
this is the second block
                         1    4    7   10
                         2    5    8   11
                         3    6    9   12
this is the third block
                         1    2    3    4
                         5    6    7    8
                         9   10   11   12

我想读取此文件并检查单词“first”、“second”和“third”，以便将以下数字 block 读入数组，以便稍后绘制它们。例如，我只想读取第二个 block 的第 1 列和第 2 列。主要问题是在第三个 block 开始之前我无法完成读入。它在秒 block 的第一行之后停止读取。简单来说，我的代码如下所示:

#include <string>
#include <fstream>
#include <istream>
#include <vector>

std::string line;
std::vector<double> vector1;
std::vector<double> vector2;
double v1;
double v2;
double v3;
double v4;

ifstream infile ("myfile.txt");
while (std::getline(infile, line)){ 
  if (line.find("second",0) != std::string::npos){    // when "second" is found start to read block.
    while (line.find_first_of("123456789.") != std::string::npos){    // while the next line is not a number continue reading. THIS DOESN'T WORK !
      infile >> v1 >> v2 >> v3 >> v4;
      vector1.push_back(v1);
      vector2.push_back(v2);
      std::getline(infile, line);
    }
  }
}
infile.close();

cout << "Vector1" << "  " << "Vector2" << endl;
for (unsigned int i = 0; i < vector1.size(); i++){
  cout << vector1[i] << "  " << vector2[i] << endl;
}

预期的结果是:

Vector1  Vector2
1        4
2        5
3        6

但是我得到:

Vector1  Vector2
1        4

Answer 1

这应该修复双重读取内部并退出循环，

ifstream infile ("myfile.txt");
while (std::getline(infile, line)) { 
    if (line.find("second",0) != std::string::npos) {
        while (infile >> v1 >> v2 >> v3 >> v4) {
            vector1.push_back(v1);
            vector2.push_back(v2);
            // note getline is removed, else double reads on break.
        }
        // this may be needed if you plan on reading anything else.
        infile.clear();
    }
}