My Function Doesn't Know My Struct Values (c++) - c++

Question

I'm new to doing structs, so please bear with me if this turns out to be a dumb question. I have one header file and four .cpp files that all include it. I have a struct called ToDoLista and it has string nameIt and int DeadLine. Then I have the things whose type name I don't know that are like, the Soccer and DropOffMax and stuff.
ToDoLista Soccer, DropOffMax, CookDinner;
Soccer.DeadLine=6;
Soccer.nameIt="SOCCER";
//and so on, for a total of six, 3 ints and 3 strings definitions.
This struct seems to be finnicky if I try to move it around because if it's in the header it's included three times and it wont run due to 'multiply defined' whatever. If I put it in one of my three non-main cpp files, it seems that the struct won't work because some of it has to be defined in main(). So now it's in my main cpp file, but I have functions that use these values, and those functions are in my non-main cpp files, which as far as I know compile before the main one. To get around that, I put the struct declaration in the header, and the definitions in my main (I may have mis-worded that) AND THEN I say 'okay, run the function 'CheckItTwice'.
//MAIN
Soccer.DeadLine=6;
//and so on for all six, like before.
//ok, NOW run the fx.
CheckItTwice(Soccer.Deadline, Soccer.nameIt);
The issue here is that if I tell CheckItTwice to say, cout the string, or the int, it runs the program without errors, but returns nothing in the console where the cout should be, because apparently they haven't been defined yet, as far as the function is concerned. Why is this/do you know a way around this?

Answer 1

In order to avoid the "defined multiply" errors you need to define your struct in a header file, and put a #pragma once or #ifndef...etc block at the top. See this here.
Include the header file in any implementation (cpp) file you plan to use the struct in.
The line
ToDoLista Soccer, DropOffMax, CookDinner;
declares three instances of the struct ToDolista, called Soccer, DropOffMax, and CookDinner. They are not types, they are instances of a type, that type being ToDolista.
I can't comment on the contents of CheckItTwice() as you didn't provide them, but look here for guidance on using cout. You might want to consider passing the struct as one argument to this method, preferrably as a const reference.

Answer 2

Define the struct in your header and #include that header in the cpp files. In the header try adding
#pragma once
at the top of your header file. This is a Microsoft specific extension - documented here
The more portable version is to add
#ifndef _SOME_DEF_
#define _SOME_DEF_
struct ToDoLista {
string namit;
string project;
int status;
int speed;
int difficulty;
int priority;
int deadline;
}
#endif // _SOME_DEF_
Be sure to remove struct definition from the .cpp file.

Answer 3

I got this issue resolved using something I saw while searching desperately online: extern. it seems that if I put the declaraction in the header, the definition in a cpp, and then declare the object again in another cpp but with 'extern' before it, it works like a charm as far as keeping the values from the original definition.
Header.h
struct ToDoLista{
string namit;
string project;
int status;
int speed;
int difficulty;
int priority;
int deadline;
};
Side.cpp
ToDoLista Pushups, Tumblr, Laundry, CleanRoom, CleanHouse, Portfolio;
void CheckItTwice(int staytus, string name){
if(staytus==1){//not on the list
staytus==2;
cout << "hurry up and" << name << " okay?" << endl;
Main.cpp
extern ToDoLista Pushups, Tumblr, Laundry, CleanRoom, CleanHouse, Portfolio;
Pushups.namit = "Push Ups";
Pushups.status = 1;
Pushups.speed = 0;
Pushups.difficulty = 0;
Pushups.priority = 0;
Pushups.project = "Get Fit";
Pushups.deadline = 20131102;
CheckItTwice(Pushups.status,Pushups.namit);
This works for me, and I hope this 'answer' helps someone else.