C++ Using a local variable of a method in another method

Question

Does anyone know if there's a way to pass a variable that i have created inside of a method to another method . I am posting part of the code so that it is clearer what i need to do

int Point::trovaLato(Point *spigolo2, Point *sol_p, Point *pvet){
//code
//code
Point* lato=new Point(myvalue1,myvalue2,myvalue3);
return 0;
}

Now i want to use that variable 'lato' inside of

int Rettangolo::interseca(Point *sol_p, Point *pvet){
int ritlat, test;
test = punti[0]->trovaLato(punti[1], sol_p, pvet); //this works
if(test){
    test = punti[1]->trovaLato(punti[2], sol_p, pvet);//ok
    if(!test){
        ritlat = lato->intersecaLato(punti[1], punti[2]); //doesn't know what lato is ofcourse :(
//more code
}

Thanks a lot

juanchopanza · Accepted Answer · 2014-08-02 16:18:07Z

1

Change the return type to Point, and return one:

Point Point::trovaLato(Point* spigolo2, Point* sol_p, Point* pvet){
  //code
  //code
  return Point(myvalue1, myvalue2, myvalue3);
}

If you really need to return an int, you can return an std::pair<int, Point>.

answered Aug 2, 2014 at 16:18

juanchopanza

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8 Comments

squirrel Over a year ago

I put 0 or 1 as return to tell me if the function found the intersection point or it didn't (which is what it does)

juanchopanza Over a year ago

You can return a sentinel Point value to indicate failure. Or an optional object. There are different approaches to solve this.

squirrel Over a year ago

the content of lato could be anything so i wouldn't know what to use as sentinel I have never used std::pair but looks like it could work. It lets me return different type. but what do i write? like return std::make_pair(0, lato); ?

juanchopanza Over a year ago

@squirrel Right. Then check thr pair's fist, and use it's second if the first indicates an intersection. But maybe use a bool instead of an int.

squirrel Over a year ago

well it gives me an error in the header file: 'pair' in namespace 'std' does not name a type

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