CODEWITHSUNDEEP
c++
JASON
JASON

Reputation: 7491

Pick next line from cin

How do I check the length of next line without extracting it from cin?

I have the input data in following form:

A
-B
--*
--C
-D
--E
---*
---F
0

And I have a recursive function to Build a tree from it.

TreeNode* BuildTree() {
  string line;
  getline(cin, line);
  char id = line[line.size() - 1];
  if (id == '0') return NULL;
  TreeNode* n = (id == '*') ? NULL : new TreeNode(id, NULL, NULL);
  if (/* This line's size less than next line's size */) {
    n->left = BuildTree();
    n->right = BuildTree();
  }
  return n;
}

Upvotes: 0

Views: 223

Answers (1)

Joe Z
Joe Z

Reputation: 17936

Write your code so that you're one line ahead. Then your if-statement becomes: 

if (/* this line's size is greater than the previous line's size */) {
   ....
}

Alternately, if you can afford the memory (and likely you can), slurp the entire file into a vector<string> and then recurse on that.

Upvotes: 3

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