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copied!<p>Your condition in the while loop is wrong. <code>ios::eof()</code> isn't predictive; it will only be set once the stream has attempted (internally) to read beyond end of file. You have to check after each<br> input.</p> <p>The classical way of handling your case would be to define a <code>>></code> function for <code>GTable</code>, along the lines of:</p> <pre><code>std::istream& operator>>( std::istream& source, GTable& dest ) { std::string line; while ( std::getline( source, line ) && line.empty() ) { } if ( source ) { std::istringstream tmp( line ); std::string name; int count; if ( !(tmp >> name >> count) ) { source.setstate( std::ios::failbit ); } else { std::vector< char > adjactentOnes; char ch; while ( tmp >> ch ) { adjactentOnes.push_back( ch ); } if ( !tmp.eof() || adjactentOnes.size() != count ) { source.setstate( std::ios::failbit ); } else { dest.Name = name; dest.Out = count; for ( int i = 0; i < count; ++ i ) { dest.AdjacentOnes.addFront( adjactentOnes[ i ] ); } } } } return source; } </code></pre> <p>(This was written rather hastily. In real code, I'd almost certainly factor the inner loop out into a separate function.)</p> <p>Note that:</p> <ul> <li><p>We read line by line, in order to verify the format (and to allow resynchronization in case of error).</p></li> <li><p>We set <code>failbit</code> in the source stream in case of an input error.</p></li> <li><p>We skip empty lines (since your input apparently contains them).</p></li> <li><p>We do not modify the target element until we are sure that the input is correct.</p></li> </ul> <p>One we have this, it is easy to loop over all of the elements:</p> <pre><code>int slot = 0; while ( slot < GTable.size() && fin >> GTable[ slot ] ) { ++ slot; } if ( slot != GTable.size ) // ... error ... </code></pre> <p>EDIT:</p> <p>I'll point this out explicitly, because the other people responding seem to have missed it: it is absolutely imperative to ensure that you have the place to read into <strong>before</strong> attempting the read.</p> <p>EDIT 2:</p> <p>Given the number of wrong answers this question is receiving, I would like to stress:</p> <ul> <li><p>Any use of <code>fin.eof()</code> <strong>before</strong> the input is known to fail is wrong.</p></li> <li><p>Any use of <code>fin.good()</code>, period, is wrong.</p></li> <li><p>Any use of one of the values read before having tested that the input has succeeded is wrong. (This doesn't prevent things like <code>fin >> a >> b</code>, as long as neither <code>a</code> or <code>b</code> are used before the success is tested.)</p></li> <li><p>Any attempt to read into <code>Gtable[slot]</code> without ensuring that <code>slot</code> is in bounds is wrong.</p></li> </ul> <p>With regards to <code>eof()</code> and <code>good()</code>:</p> <p>The base class of <code>istream</code> and <code>ostream</code> defines three “error” bits: <code>failbit</code>, <code>badbit</code> and <code>eofbit</code>. It's important to understand when these are set: <code>badbit</code> is set in case of a non-recoverable hardward error (practically never, in fact, since most implementations can't or don't detect such errors); and <code>failbit</code> is set in any other case the input fails—either no data available (end of file), or a format error (<code>"abc"</code> when inputting an int, etc.). <code>eofbit</code> is set <strong>anytime</strong> the <code>streambuf</code> returns <code>EOF</code>, whether this causes the input to fail or not! Thus, if you read an <code>int</code>, and the stream contains <code>"123"</code>, without trailing white space or newline, <code>eofbit</code> will be set (since the stream must read ahead to know where the <code>int</code> ends); if the stream contains <code>"123\n"</code>, <code>eofbit</code> will not be set. In both cases, however, the input succeeds, and <code>failbit</code> will not be set.</p> <p>To read these bits, there are the following functions (as code, since I don't know how to get a table otherwise):</p> <pre><code>eof(): returns eofbit bad(): returns badbit fail(): returns failbit || badbit good(): returns !failbit && !badbit && !eofbit operator!(): returns fail() operator void*(): returns fail() ? NULL : this (typically---all that's guaranteed is that !fail() returns non-null.) </code></pre> <p>Given this: the first check must always be <code>fail()</code> or one of the <code>operator</code> (which are based on <code>fail</code>). Once <code>fail()</code> returns true, we can use the other functions to determine why:</p> <pre><code>if ( fin.bad() ) { // Serious problem, disk read error or such. } else if ( fin.eof() ) { // End of file: there was no data there to read. } else { // Formatting error: something like "abc" for an int } </code></pre> <p>Practically speaking, any other use is an error (and any use of <code>good()</code> is an error—don't ask me why the function is there).</p>

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