return value from function

[adam2016]

Hi guys I've got a dilemma I want to get the return value of a function and set it equal to a pointer in main,I know this can be achieved using a global pointer but I want to avoid using globals in this small project,

is there any way I can get the return value of the function without the function actually being displayed to the console?

thanks

  map<string,string>* readFromDiary(){

	map<string, string> entries;
	ifstream in;
	string date;
	string description;
	string fileName = "diary.txt";

	in.open(fileName);

	if (!in.is_open()) {

		cout << "file could not be opened" << endl;
		return NULL;
	}

	while (in) {

		getline(in, date, ':');
		getline(in, description);
		if (!in) {
			break;
		}
		cout << date;
		cout << description;
		cout << endl;

		entries[date] = description;
	}
	return &entries;
}


void openDiary(){




}

int main() {

	bool quit = false;
	map<string,string>* entries;

	while(!quit){

		entries = readFromDiary();

	}

}

[coder777]

Do not return a pointer to a local object. You can simply return the object itself:

  map<string,string> readFromDiary(){ // Note: no *

	map<string, string> entries;

...

	return entries; // Note: no &
}

...

int main() {

	bool quit = false;
	map<string,string> entries; // Note: no *

	while(!quit){

		entries = readFromDiary();

	}

}

Due to the move semantic it is nearly as effecient as returning a pointer because the content is not copied but moved.

[Chervil]

Alternatively pass by reference. Again, no pointer.

#include <iostream>
#include <string>
#include <map>
#include <fstream>

using std::cout;
using std::endl;
using std::string;
using std::map;
using std::ifstream;

bool readFromDiary( map<string, string>& entries)
{
    string fileName = "diary.txt";
    ifstream in(fileName);
    if (!in)
    {
        cout << "file " << fileName << " could not be opened" << endl;
        return false;
    }


    string date;
    string description;

    while ( getline(in, date, ':'), getline(in, description) )
    {
//      cout << date;
//      cout << description;
//      cout << endl;

        entries[date] = description;
    }
    return (entries.size() != 0);
}

int main()
{
    map<string,string> entries;

    bool ok = readFromDiary(entries);
    
    if (ok)
        for (const auto & entry : entries)
            cout << entry.first << " ..... " << entry.second << '\n'; 
    else
        cout << "No entries\n";         
}

[adam2016]

thanks guys =)