Using loops and control constructs

For the for-loop index variable:

Use a long type variable whenever possible. Under ILP32, long and int are equivalent, but long is better for portability to an LP64 environment.
Use the auto or register storage class over the extern or static storage class.
If you use an enum variable, expand the variable to be a fullword by using the ENUMSIZE compiler option or by placing a large defined value at the end of your enum variable, as follows:
```
enum animals {

ant

cat,

dog,

robin,

last_animal = INT_MAX;

};
```
Do not use the address operator (&) on the index.
The index should not be a member of a union.

For if statements: