difference

n 1: the quality of being unlike or dissimilar: "there are many

differences between jazz and rock" [ant: {sameness}]

2: a quantity obtained by subtraction; "profit is a positive

difference between income and expenses"

3: a variation that deviates from the standard or norm; "the

deviation from the mean" [syn: {deviation}, {divergence},

{departure}]

4: a disagreement or argument about something important; "he

had a dispute with his wife"; "there were irreconcilable

differences"; "the familiar conflict between Republicans

and Democrats" [syn: {dispute}, {difference of opinion}, {conflict}]

5: a significant change; "the difference in her is amazing";

"his support made a real difference"

dereference

To access the thing to which a pointer points,

i.e. to follow the pointer. E.g. in {C}, the declarations

int i;

int ▫p ◦ &i;

declare i as an integer and p as a pointer to integer. p is

initialised to point at i ("&i" is the address of i - the

inverse of "▫"). The expression ▫p dereferences p to yeild i

as an {lvalue}, i.e. something which can appear either on the

left of an {assignment} or anywhere an integer expression is

valid. Thus

▫p ◦ 17;

would set i to 17. ▫p:: is not the same as i:: however since

it is parsed as ▫(p::), i.e. increment p (which would be an

invalid thing to do if it was pointing to a single int, as in

this example) then dereference p's old value.

The {C} operator "->" also dereferences its left hand argument

which is assumed to point to a {structure} or {union} of which

the right hand argument is a {member}.

At first sight the word "dereference" might be thought to mean

"to cause to stop referring" but its meaning is well

established in jargon.

(1998-12-15)