When I don't care too much about speed, I handle that type of thing in distinct re-usable functions (from a lack of deep familiarity with proper stream usage).
In your case, I might do it like this:
//Load the file into a single string.
std::string fileContents = LoadFileAsString("text.txt");
//Remove comments.
fileContents = String::RemoveComments(fileContents, "//");
fileContents = String::RemoveComments(fileContents, "/*", "*/");
//Seperate the string into lines; this also eliminates empty lines via a callback function.
StringList lines = String::Seperate(fileContents, '\n', RemoveEmptyLines);
if(lines.empty())
{
//The file (barring empty lines and comments) is empty!
//Handle the error.
}
//Get the first line.
int line = 0;
int numberOfFiles = StringToInt(lines[line++]); //You can also use lines.at() and catch the exception for malformed files.
if(lines.size() > (line + numberOfFiles))
{
//Malformed file. Not as many lines as promised by 'numberOfFiles'.
//Handle the error.
}
//Find the iterators to the range of files we want.
auto beginningOfFiles = (lines.begin() + line);
auto endOfFiles = (beginningOfFiles + numberOfFiles);
//Copy the range of elements to their own vector.
StringList files;
std::copy(beginningOfFiles, endOfFiles, files.begin());
//Continue processing the file...
line += numberOfFiles;
//...more file processing...
Most of those functions exist already exist in my code base through repeated needs, though RemoveComments() does not (I've never had to deal with multi-line comments before, but that's easy enough to solve - and once solved, becomes a permanent tool in your library, ready to use).
String::Seperate() function. Currently just takes a boolean to check for empty lines, but after writing this post I realize I need a callback function to check for non-empty but whitespace-filled lines. I also have it on my todo list (but as low priority) to make a version for if 'divider' is a single char (which would be alot faster).
StringList is just a typedef for
std::vector<std::string> since I use it so often.
//Divides up a string into multiple segments seperated by 'divider', and returns each segment in a StringList.
//If any segment is empty, and if 'ignoreEmptySegments' is true, the empty segments are not added to the StringList.
StringList Seperate(const std::string &str, const std::string ÷r, bool ignoreEmptySegments)
{
StringList stringList;
//Check for empty string.
if(str.empty() || divider.empty())
return stringList;
size_t start = 0;
size_t end = str.find(divider, start);
//Keep looping, as long as there are more segments.
while(end != std::string::npos)
{
std::string subString = str.substr(start, end - start);
if(subString.size() > 0 || ignoreEmptySegments == false)
{
stringList.push_back(subString);
}
start = end + 1;
end = str.find(divider, start);
}
//Get the final (or the only) segment.
std::string subString = str.substr(start, str.size() - start);
if(subString.size() > 0 || ignoreEmptySegments == false)
{
stringList.push_back(subString);
}
return stringList;
}
LoadFileAsString() function.
//Loads the entire file, newlines and all, and returns its contents as a string.
//Returns an empty string if the file doesn't exist.
std::string LoadFileAsString(const std::string &filename, ReadMode::Enum readMode)
{
//Open the file for reading.
std::ifstream file;
if(readMode == ReadMode::Binary)
file.open(filename.c_str(), std::ios_base::in | std::ios_base::binary);
else
file.open(filename.c_str(), std::ios_base::in);
if(!file)
{
Log::Message(MSG_SOURCE("FileFunctions", Log::Severity::Error)) << "Failed to load '" << Log_HighlightCyan(GetFilenameFromPath(filename)) << "' at " << Log_DisplayPath(filename)
<< "\nDo I have sufficient privileges? Does the file even exist?" << Log::FlushStream;
return "";
}
//Read the file into the stringStream.
std::ostringstream stringStream;
stringStream << file.rdbuf();
//Convert the stringStream into a regular string.
return stringStream.str();
}
Observant programmers will notice that most of my code suffers from
[s]Shmuel[/s] Schlemiel the Painter algorithms. Many of the functions could be individually optimized, and the use of them together could further be optimized into a stand-alone function, like a "LoadFileAsStringList()" since I frequently go from File to String to StringList (easy enough to add).
I typically prefer clean code that works before I start optimizing code, and I don't do the actual optimizations until I find them necessary (otherwise I find myself wasting inordinate amounts of time of things that don't matter much). With file parsing, when I occasionally need files parsed fast, I load it as binary and don't bother with text parsing anyway.
