C++ :: How To Convert Char To Const Char

I have a file which contains a year and the name of an associated file to be read. I need to extract the data in the txt file and perform some calculations.

（ year data file）
2004 2004data.txt
2005 2005data.txt
2006 2006data.txt

Here is what I do. I first declare "char yeardata" and then pass "2004data.txt" to it. Then I call yeardata in ifstream to extract the data inside the file "2004data.txt". The problem is that char yeardata is not constant so I cannot pass the file to it. It doesn't work if I change "char yeardata" to "const char yeardata".

Code:
int oldnewcomp_temp(char* lcfile) {
using namespace std;

int year;
char yeardata;

[Code] ....