Passing input file name as parameter

I suppose also that your question could be interpreted as "how do I pass the filename in as a parameter to the main() function?"

This is possible using the optional argc and argv parameters which will get filled with the command line arguments.

For example, if you declare you main function as:

int main( int argc, char *argv[] )

Then argc will contain the number of command line arguments (in addition to the program name, so argc should be >= 1) and argv is an array of strings with argc elements that contains the arguments.

For example, if you executable was called "a.out" and you called it as such:

> a.out blahblah output.dat "foobar roobar"

Then argc would be "4" (3 arguments + command name) and argv would be as follows:

argv[0] = "a.out"
argv[1] = "blahblah"
argv[2] = "output.dat"
argv[3] = "foobar roobar"

(note that the quotes do not appear in the string, i've included them here only to delimit the string)

I guess I mislead you. What I meant by was like this:
----------------------

void ReadInputFile(const char * generated_data_file)
{
 ifstream inFile(generated_data_file);
}

int main()
{
…
char[] generated_data_file = "input.dat";
ReadInputFile(generated_data_file);
…
}
----------------------------
this gives me error like this:

AnalyzeOutput.cpp: In function `void ReadInputFile(basic_string<char,string_char
_traits<char>,__default_alloc_template<false,0> >)':
AnalyzeOutput.cpp:22: no matching function for call to `ifstream::ifstream (stri
ng &)'
/usr/local/lib/gcc-lib/sparc-sun-solaris2.8/2.95.2/../../../../include/g++-3/fst
ream.h:61: candidates are: ifstream::ifstream()
/usr/local/lib/gcc-lib/sparc-sun-solaris2.8/2.95.2/../../../../include/g++-3/fst
ream.h:62:                 ifstream::ifstream(int)
/usr/local/lib/gcc-lib/sparc-sun-solaris2.8/2.95.2/../../../../include/g++-3/fst
ream.h:63:                 ifstream::ifstream(int, char *, int)
/usr/local/lib/gcc-lib/sparc-sun-solaris2.8/2.95.2/../../../../include/g++-3/fst
ream.h:65:                 ifstream::ifstream(const char *, int = ios::in, int =
 436)
/usr/local/lib/gcc-lib/sparc-sun-solaris2.8/2.95.2/../../../../include/g++-3/fst
ream.h:68:                 ifstream::ifstream(const ifstream &)
AnalyzeOutput.cpp: In function `int main()':
AnalyzeOutput.cpp:77: parse error before `['
AnalyzeOutput.cpp:80: `generated_data_file' undeclared (first use this function)
AnalyzeOutput.cpp:80: (Each undeclared identifier is reported only once
AnalyzeOutput.cpp:80: for each function it appears in.)

Thank you pointing out my mistake.