Basic C++ Function Pointers & Struct

Question

I'm having issues passing an array struct into a function for processing.

I think I need to pass the function the address of the array, however have got multiple compiler errors and am running out of combinations to try.

The function then needs to return a value to a new struct member.

Here is my best shot!

  //-----------------

  void Function(struct MyStruct* ptr);

  //------------------

  int main(){

  MyStruct array[MAX];

for (int i=0; i<MAX; i++)
{

    File>>array[i].V1;
    File>>array[i].V2;
    File>>array[i].V3;
    File>>array[i].V4;
    MyStruct* ptr = &array[i];
    array[i].V5 = Function(ptr);
}
  }

  //-----------------------

  void Function(struct MyStruct* ptr)
  {
  // do something with the struct, how to I access each element in here?
  }

Thanks!

Your main looks good. Don't forget to give Function a useful return type that'll match array[i].V5, and inside it you may access the members of MyStruct through the pointer like ptr->V1, ptr->V2 etc — Lightness Races in Orbit
– Lightness Races in Orbit, Commented Jan 24, 2012 at 0:57

chrisaycock · Accepted Answer · 2012-01-24 00:55:22Z

1

You have a void type for Function, which is why you can't return anything. You should make it return whatever V5's type is instead.

Also, to access a element of ptr, use the arrow notation:

ptr->V5

answered Jan 24, 2012 at 0:55

chrisaycock

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3 Comments

user1055774 Over a year ago

Thanks for the reply. Within my function: ptr->V5 = 1.0; gives error C2227: left of '->V5' must point to class/struct/union/generic type. This would save me having to define return types, which is what I want to do. Thanks!

chrisaycock Over a year ago

@user1055774 How are you defining MyStruct? You should update your question to feature your full code.

user1055774 Over a year ago

Sorry, that's me. I had assigned a value that was of an incorrect type. The code is now working, sometimes you just need someone to point out the obvious. Thanks!

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