Re: std::ifstream
Fil wrote:
Thanks a lot. I trust that ifstream will be able to find the length of the
string by itself.
Usually when I am passing an array to a function through a pointer I also
pass the length.
int linesCount(const std::string& filePath)
{
std::ifstream inFile(filePath.c_str());
std::string line;
int count(0);
while (std::getline(inFile,line))
{
count++;
}
return count;
}
That's cool, it works perfectly.
Note that you should pass the string by const reference here, to avoid
unnecessary copy.
I am not sure why but I hope it is explained somewhere in my textbook
("Thinking in C++"). Thanks again.
Fil:
The c_str() member function of std::string outputs the contents of the string
followed by a nul character.
When you pass function arguments by value, a copy of the object is made. Copying
std::string can (depending on the compiler and/or string length) cause a memory
allocation, so it is quite expensive. If you pass by reference, this copy does
not happen (just like passing by address (pointer) in C). If you pass by const
reference, the receiver cannot modify the contents of the string, so there is no
difference as far as the sender is concerned. Always pass by const reference
when you can.
--
David Wilkinson
Visual C++ MVP