C++ - 反复使用 istringstream

问题描述

我有一个代码用于读取在线存储的带有浮点数的文件:3.34|2.3409|1.0001|...|1.1|".我想使用 istringstream 来读取它们，但它不像我期望的那样工作:

I have a code for reading files with float numbers on line stored like this: "3.34|2.3409|1.0001|...|1.1|". I would like to read them using istringstream, but it doesn't work as I would expect:

  string row;
  string strNum;

  istringstream separate;  // textovy stream pro konverzi

   while ( getline(file,row) ) {
      separate.str(row);  // = HERE is PROBLEM =
      while( getline(separate, strNum, '|') )  { // using delimiter
        flNum = strToFl(strNum);    // my conversion
        insertIntoMatrix(i,j,flNum);  // some function
        j++;
      }
      i++;
    }

在标记点，仅第一次将行复制到单独的流中.在下一次迭代中，它不起作用并且什么也不做.我希望可以在每次迭代中不构建新的 istringstream 对象的情况下使用更多次.

In marked point, row is copied into separate stream only first time. In next iteration it doesn't work and it does nothing. I expected it is possible to be used more times without constructing new istringstream object in every iteration.

推荐答案

将行设置到 istringstream 后...

After setting the row into the istringstream...

separate.str(row);

...通过调用重置它

separate.clear();

这会清除在前一次迭代中或通过设置字符串设置的任何 iostate 标志.http://www.cplusplus.com/reference/iostream/ios/clear/

This clears any iostate flags that are set in the previous iteration or by setting the string. http://www.cplusplus.com/reference/iostream/ios/clear/

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