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struct members by reference

General and Gameplay Programming Programming

Started by icecubeflower July 26, 2008 10:48 PM

3 comments, last by icecubeflower 15 years, 8 months ago

icecubeflower

100

Author

July 26, 2008 10:48 PM

What if you have this struct:


struct Speckeeper
{
   Iceint icespec[3];  //not all three are always used
   string name;
};

Now say you have this function:


void stupidfunction(string &strfun, ifstream &infile)
{
   int ix;

   strfun="Data/";
   ix=5;
   while(strfun[ix-1]!=' '&&ix<20)
   {
      strfun+=infile.get();
      ix+=1;
   }
   strfun.resize(ix-1);
}

Could you go like this?:


Speckeeper skulls;
ifstream dumbfile;

stupidfunction(skulls.name, dumbfile);

What I'm pointing out is the the string is pass by reference in that function. So does that mean after stupidfunction goes out of scope the value of skulls.name will be changed?

AndyPandyV2

298

July 26, 2008 10:52 PM

If you wrote the code why didn't you just test it? Yes you do this.

icecubeflower

100

Author

July 26, 2008 11:00 PM

I don't have access to my computer. I'm on my sister's windows box and I'm reading a C++ book but it's really hard to read.

Aardvajk

13,217

July 27, 2008 04:06 AM

Yes, you can pass a struct or class member into a function taking a parameter by reference the same as any other variable. Equally, you can pass the address of a struct or class member to a function expecting a pointer.

void f(std::string &s){    s="hello";}void g(int *i){    (*i)=23;}struct test{    std::string text;    int value;};int main(){    test t;    f(t.text);    g(&(t.value));    std::cout << t.text << "\n" << t.value << "\n";}

The above will output:

hello
23

much as you would expect.