Lecture 9.md

Lecture 9 - Oct. 13, 2015

Reviewing C concepts.

Notice the difference between const int *p and int * const p

const int *p is a pointer to a constant integer.

int * const p is a constant pointer to an int. You can manipulate the value of the int but you cannot change the address that the pointer points to.

Tip: read from the variable to the left.

Rule: const applies to the thing on the left unless there is nothing to the left, then it applies to the right.

References

Note about references: they are constant.

Cannot change what the reference points to.

Think of it as: constant pointer with automatic dereferencing.

A reference is an alias. It is another name for what it is referencing.

Reference cannot be uninitialized.

Cannot create:

• Pointers to a reference
• Reference to reference
• Array of references

Remember to declare references as const if the value need not change. (MARKS MAY BE LOST IF NOT DONE).

When to allocate memory in the heap

Always allocate on the stack unless:

1. The value must outlive the variable scope
2. If size of collection/array is unknown or subject to resizing
3. Memory allocation is too big for the stack