DaniWeb Forum Index > Software Development > C++

C++ RSS

Passing a filename to a function

Please support our C++ advertiser: Intel Parallel Studio Home

•

Join Date: Jan 2009

Posts: 1

Reputation: adarrell is an unknown quantity at this point

Solved Threads: 0

adarrell

Offline

Newbie Poster

Passing a filename to a function

Jan 30th, 2009

Hi, I have been trying for several hours without success to write a function that takes a filename, opens the corresponding file, populates a std::vector<double> with values from the file, and returns the std::vector<double>. I can't get past the passing the filename stage unfortunately, despite reading about this here there and everywhere online.

Could anybody give me a clue how to do this please?

Thanks!

•

Join Date: Jan 2009

Posts: 16

Reputation: venomxxl is an unknown quantity at this point

Solved Threads: 2

venomxxl

Offline

Newbie Poster

Re: Passing a filename to a function

Jan 30th, 2009

You can do this by passing a pointer to char or a string.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <string>
void yourFunction(const char * filename); //we don't want to modify so it's const
void yourFunction(string filename);
#include <string>
void yourFunction(const char * filename); //we don't want to modify so it's const
void yourFunction(string filename);

•

Join Date: Oct 2006

Posts: 2,853

Reputation: niek_e has a reputation beyond repute

Solved Threads: 301

niek_e

Offline

Roasting Maven

Re: Passing a filename to a function

Jan 30th, 2009

Also, if you're using std::strings for a filename you'll have to convert them to const char* for ifstream. The c_str() function will do that for you:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
    std::string filename = "my_file.txt";
    std::ifstream infile(filename.c_str());
    std::string filename = "my_file.txt";
    std::ifstream infile(filename.c_str());