Getting Memory

In C, malloc(n) returns the address of a block of memory of size n bytes.

Pointer Variables

A pointer variable can hold an address, e.g. as returned by malloc. In C,

                float X;

declares X to be a variable containing a floating point value, and

                float *X

declares X to be a variable containing the address of a floating point value.

Invalid Address

NULL can be stored in a pointer, but is not a valid address. It is useful to indicate the end of a chain of pointers. Use P=NULL; to store it, and if (P == NULL) ... to test it.