std::ifstream

Hi,

I am learing C++ with Thinking in C++ (Bruce Eckel) and we've done some
exercises on ifstream in the past chapter.
If I pass to my ifstream object a constant filePath (as we did in he book)
it works, but it doesn't as soon as I pass it a variable.
I have got one error araising from linesCount.cpp, line 6.

main.cpp
-------------------------------------------------------------------------------------
#include "linesCount.h"

int main()
{
    return linesCount("C:\\TICPP-2nd-ed-Vol-one\\html\\Frames.html");
}
-------------------------------------------------------------------------------------

linesCount.h
-------------------------------------------------------------------------------------
#include <string>
int linesCount(std::string filePath);
-------------------------------------------------------------------------------------

linesCount.cpp
-------------------------------------------------------------------------------------
#include <string>
#include <fstream>

int linesCount(std::string filePath)
{
    std::ifstream inFile(filePath);
    std::string line;
    int count(0);
    while (std::getline(inFile,line))
    {
        count++;
    }
    return count;
}
-------------------------------------------------------------------------------------

The error message is:

linescount.cpp(6) : error C2664:
'std::basic_ifstream<_Elem,_Traits>::basic_ifstream(const char
*,std::ios_base::openmode,int)' : cannot convert parameter 1 from
'std::string' to 'const char *'
        with
        [
            _Elem=char,
            _Traits=std::char_traits<char>
        ]
        No user-defined-conversion operator available that can perform this
conversion, or the operator cannot be called

Can you please help?
Thank you.