[RESOLVED] How do you cycle through an array of objects?

[gjon]

            foreach (Room q in rooms)
            {
                rooms[q].rWall = "|";
                rooms[q].floorDwn = "_";
            }

When I try Room I get the error:
Cannot implicitly convert type 'MazeGen.Room' to 'int'

And when I try int q in rooms I get the error:
Cannot convert type 'MazeGen.Room' to 'int'

Thank you in advance for showing me how to cycle through the index of an array.
I have seen it to be done like this:
foreach (char ch in str)

but I'm not able to resemble it in this case.

[jmcilhinney]

The whole point of a foreach loop is that the loop counter IS the item from the list. Youre' treating it like a for loop, where the loop counter is an index that you use to get the item. As this part says:

foreach (Room q in rooms)

the q variable IS the Room object, not an index into the array to get a Room object. Your code should be:

foreach (Room q in rooms)
            {
                q.rWall = "|";
                q.floorDwn = "_";
            }

[gjon]

I tried to do as you have written but I am getting the error:

Cannot modify members of 'q' because it is a 'foreach iteration variable'

[jmcilhinney]

Can you show us the type definition for Room?

[jmcilhinney]

OK, I just did some testing of my own and it seems that you can set fields/properties of reference types, i.e. classes, in a foreach loop like that but you can't do so with value types, i.e. structures. Thus I assume that your Room type is a structure.

This is explained by the fact that in your code q will be a copy of the actual value in the array, so setting its fields/properties is pointless because it will not affect the original. If you want to change fields/properties of an array of structures then use a for loop instead of a foreach loop:

[gjon]

You are right. It is an array of structures.

I didn't realize this before but your explanation was very helpful.


Thanks so much.

[penagate]

You shouldn't use structures unless its absolutely essential that they have value type semantics. Reference types are superior in most situations.

[gjon]

Thank you for that advice.