C++ - 反复使用 istringstream

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.

separate.str(row);

separate.clear();