我无法从文本文件中读取行吗？

Question

I want to read in a line from a text file, store the line in an array of strings to later display the line numbers a word can be found on, and also break down the line into words for marking how many times unique words come up. I have successfully been able to break down the lines word by word and mark the frequency in which they appear but I'm struggling with storing the line in an array of strings so that I can use it later.

void get_word(istream& in_stream, string& w,
              list<string> &wordlist, int& lineCount, string *line)
{

  string t;
  getline(in_stream,t);

  for (int j=0; t[j]; j++)
    t[j] = tolower(t[j]);

  line = &t;
  istringstream iss(t);
  string word;
  while(iss >> word) 
  {
    insert_word(word, wordlist);
  }

}

So far this is what I have and no matter what I try to do with the line where I try to assign the string "t" to the "line" array that's being pointed to it doesn't put anything in the array, I think I'm just completely missing something. line is initialized as:

string line[0];

Answer 1

First of all, string line[0] gives you an array of no strings. That's not likely to be what you intended. Why not simply string line ? That's one string. You'd pass a pointer to that string into your function, with &line .

Secondly, line = &t replaces the input pointer with a pointer to the local variable. This information is lost once the function ends. If you write *line = t then you are instead setting "the string that line points to" to the value of "the string t ".

Ideally you'd avoid the "out argument" and just return the string you want, though.