Question

My problem is how to use correctly the function infile.open().

I have a class that, among the others, has the following public properties:

class myclass {
public:
int rows
int columns
const char* array_file
}

All values are given at run-time.

When I call the function that uses a member of the class I have (pt is a pointer to a member of the class)

#include <vector>
#include <fstream>
#include <iostream>
typedef std::vector< std::vector<int> > Matrixint;

void function(myclass* pt) { 
    Matrixint array_name(pt->rows, std::vector<int>(pt->columns));

    std::ifstream infile;

    infile.open("%s", pt->array_file); // my problem: is this correct?
    for (int a = 0; a < pt->rows; a++) {
         for (int b = 0; b < pt->columns; b++) {
               infile >> array_name[a][b] ;
         }
    }
    infile.close();

}

Is this way of opening/reading the file correct?

The data in the file will be formatted as in this question (please note: only the array will be present in the file, no other data)

Answer 1

infile.open gets as its first parameter the filename:

void open ( const char * filename, ios_base::openmode mode = ios_base::in );

(source)

I don’t know what your filename is but maybe something like this (just a guess based on variable types) could do:

infile.open(pt->array_file); 

of course you have to ensure that the filename you pass in is correct at the time of calling that function.