loading vectors and data before main

I have a series of datasets that I load like this:

ifstream code that looks like this in the beginning of main

Code:

---

int main
{
 vector<vector<bool >> setbool;
ifstream setboolCSV ("setboolcsv.csv");
linenum = 0;
itemnum = 0;
while (getline (setboolCSV, line))
    {
        ++linenum; //increment the line count
        setbool.resize(linenum);

        istringstream linestream(line);
        itemnum = 0;
        while (getline (linestream, item, ','))
                {
                        ++itemnum; //increment the item count
                        setbool[linenum-1].resize(itemnum);
                        const char *pitem = item.c_str();
                        doubleitem = atof(pitem);
                        setbool[linenum-1][itemnum-1] = doubleitem;
                       
                }
       
        }

setboolCSV.close();
...
return 0;
}
end of code

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however classes that I create will be reliant on values in setbool based on indexes that i create. Is there a way to create bool before main, but pass it into main as well as any class header files that i create? what i am trying to avoid is if I have 10 classes that uses setbool[X][Y] to make a decision, i don't want to create 10 instances of setbool.

this code works as is - any thoughts also on how to structure to clean up main ? i realize that it is not best to convert from double into bool, but it is ok b/c my file is 1s and 0s. 0s will turn into false, 1s into true. if there is better way to write please let me know.

Quote:

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Is there a way to create bool before main, but pass it into main as well as any class header files that i create?

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Make it global ?
You could create a header files containing your global variable and declare it as extern where you want to use it.

Quote:

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Originally Posted by Spidey

Make it global ?
You could create a header files containing your global variable and declare it as extern where you want to use it.

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how to declare it as external? do you have code example of declare?

Quote:

---

Originally Posted by lawrenced

I have a series of datasets that I load like this:

ifstream code that looks like this in the beginning of main

Code:

---

int main
{
 vector<vector<bool >> setbool;
ifstream setboolCSV ("setboolcsv.csv");
linenum = 0;
itemnum = 0;
while (getline (setboolCSV, line))
    {
        ++linenum; //increment the line count
        setbool.resize(linenum);

        istringstream linestream(line);
        itemnum = 0;
        while (getline (linestream, item, ','))
                {
                        ++itemnum; //increment the item count
                        setbool[linenum-1].resize(itemnum);
                        const char *pitem = item.c_str();
                        doubleitem = atof(pitem);
                        setbool[linenum-1][itemnum-1] = doubleitem;
                       
                }
       
        }

setboolCSV.close();
...
return 0;
}
end of code

---

however classes that I create will be reliant on values in setbool based on indexes that i create. Is there a way to create bool before main, but pass it into main as well as any class header files that i create? what i am trying to avoid is if I have 10 classes that uses setbool[X][Y] to make a decision, i don't want to create 10 instances of setbool.

this code works as is - any thoughts also on how to structure to clean up main ? i realize that it is not best to convert from double into bool, but it is ok b/c my file is 1s and 0s. 0s will turn into false, 1s into true. if there is better way to write please let me know.

---

If the class requires values from the data file, then you're going to have to wait until you read the data file (which will be after main starts). You can create instances of the class at any time, including after the file is read.

Why are you reading 1's and 0's via double? Why not just read it in as a bool?

You should pass it by reference to the classes that need it. You can either pass it into the class functions that need that data, or pass it in their constructor and let them store a reference to it.

Also, I would look into the push_back function for vector. I think you'll like it better than using resize so much.

Quote:

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Originally Posted by tabstop

Why are you reading 1's and 0's via double? Why not just read it in as a bool?

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because I don't know how to do this? is there a way?

Here's a website with many of the most common C++ data types.

Quote:

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Originally Posted by lawrenced

because I don't know how to do this? is there a way?

---

Code:

---

#include <iostream>
#include <sstream>
#include <iomanip>

int main() {

    std::stringstream foo;
    foo << "1 0 0 0 0 1 1 1 1 0 0";
    bool bar;
    while (foo >> bar) /*ooh reading into a bool!*/{
        std::cout << std::boolalpha << bar << std::endl;
    }
    return 0;
}

---

Quote:

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Originally Posted by Spidey

Make it global ?
You could create a header files containing your global variable and declare it as extern where you want to use it.

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Not a good idea. The initialization of objects is implemention-defined, so it's impossible to guarantee the file has been opened before using it.
I would delay creating the classes until the file has been opened, and pass it as arguments to the constructors of the classes.