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    <p>First and foremost, your program is wrong. After the <code>while</code> loop ends, there is nothing more to read in the file (unless you <code>seekg()</code> back to the beginning), so the <code>std::getline()</code> call in the <code>for</code> loop body basically does nothing.</p> <p>A second problem is that concerns are not properly separated.</p> <p>Here is how I would have implemented this program:</p> <pre><code>struct line_data { Time t; double x; }; // This handles reading a single Time value. std::istream &amp; operator &gt;&gt; (std::istream &amp; is, Time &amp; t) { int hh, mm; if (is &gt;&gt; hh &gt;&gt; mm) { // Not happy with the following two lines, too Java-like. :-( t.setTimeHours(hh); t.setTimeMinutes(mm); } return is; } // This handles reading a single line of data. std::istream &amp; operator &gt;&gt; (std::istream &amp; is, line_data &amp; ld) { std::string s; if (std::getline(is, s)) { std::istringstream iss(s); // Ensure errors are propagated from iss to is. if (!(iss &gt;&gt; ld.t &gt;&gt; ld.x)) is.setstate(std::ios::failbit); } return is; }; // This handles processing a single line of data. struct line_manip // satisfies concept OutputIterator&lt;line_data&gt; { std::back_insert_iterator&lt;std::vector&lt;Time&gt;&gt; ti; std::back_insert_iterator&lt;std::vector&lt;double&gt;&gt; xi; line_manip(std::vector&lt;Time&gt; &amp; ts, std::vector&lt;double&gt; &amp; xs) : ti(std::back_inserter(ts)) , xi(std::back_inserter(xs)) { } line_manip &amp; operator = (const line_data &amp; ld) { ti = ld.t; xi = ld.x; return *this; } line_manip &amp; operator * () { return *this; } line_manip &amp; operator ++ () { return *this; } line_manip &amp; operator ++ (int) { return *this; } }; int main() { std::ifstream ifs("input.txt"); std::vector&lt;Time&gt; ts; std::vector&lt;double&gt; xs; std::copy(std::istream_iterator&lt;line_data&gt;(ifs), std::istream_iterator&lt;line_data&gt;(), line_manip(ts, xs)); // ... } </code></pre>
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