Declaring an variable number of variables

I am writing a program that will analyze a simple map that will be defined by a sequential data file. Each data file may have a different number of vertices and legs.

For example, the 'map' that looks like a plus-sign would have 5 vertices and 4 legs. I need to define variables, something along the lines of vert1, vert2, ... , vert5, leg1, ... , leg4.

I tried using the token-pasting operator in a loop to declare the variables, but I must be doing something wrong. First, it seems to want me to declare vert and leg as variables before it will paste. That I can understand, and it wouldn't cause any problems. However, when I do that, I end up with variables like 'legloop' of 'vertn' (where loop or n are the loop controlling variables) instead of leg1 or vert6.

Is the token paster the way to go here?
If so, how should it be used?
If not, what method should I use?

:confused:

Arrays are what you'd want to use in this situation. In C++ at least, you can have arrays without expressly specifying the size of the array, so they should be all you'd need.

http://www.cprogramming.com/tutorial/lesson8.html

you mean youre using foo## bar ?
thats the wrong way to do it.
that ## operator is something the preprocessor applies.
thus the token will be pasted before it is sent to the compiler.

you might want to used the std::string object for string concatenation

Actually sean you have to specify the size of the array. You however can dynamically allocate an array using new.

Tokenizing won't work because it simply appends the two text portions together. Why don't you allocate the number of variables dynamicly, and use them like an array? Or why not use a linked list, or a vector? If you don't know what an array is, here's how it works:

Say we need five integers. We could do this:

Code:

---

int v1, v2, v3, v4, v5;

v1 = 0;
v2 = 3;
v3 = 6;
v4 = 9;
v5 = 12;

---

Or whaver you like for your initializations. Or we could use an array:

Code:

---

int vars[5]; // make 5 integers, grouped under the name 'vars'.

vars[0] = 0;    // you index them starting with zero...
vars[1] = 3;
vars[2] = 6;
vars[3] = 9;
vars[4] = 12;    // indexing through "size -1", in this case 4. (5 - 1 == 4)

---

Quzah.

I feel like such a fool.
I can have the size of the array in the data file, so that's not a problem.

Thanks for the help.

Quote:

---

Originally Posted by sean_mackrory

Arrays are what you'd want to use in this situation. In C++ at least, you can have arrays without expressly specifying the size of the array, so they should be all you'd need.

---

Only if you define a string after the assignment operator...it'll fill in the appropriate amount of elements for you.

Else, you need to declare the number of elements. :cool:

I think sean meant the leaving out the number actual number in the middle and letting the compiler determine how large the array needs to be. At least I hope so :)

The impression I got was:

Code:

---

int size;
cin >> size;
int arr[size];

---

Which isn't standard.