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William Vedder wrote:
>What does "+=" mean?
>What does "/=" mean?
C, C++, and Java have shortcuts for arithmetically changing the
value of a variable. Here is how they work. If you will be doing
more of these translations to EL you will see these often:
++a or a++ is the same as a = a + 1
--a or a-- is the same as a = a - 1
a += b is the same as a = a + b
a -= b is the same as a = a - b
a *= b is the same as a = a * b
a /= b is the same as a = a / b
...and so on for every operator between two values. These would also
include the binary operators &, |, ^, <<, >> (AND, OR, Exclusive OR,
bit-shift to left, bit-shift to right) as &=, |=, ^=, <<=, and >>=.
The reason for these shortcuts is that they compile into more
efficient machine code than the "standard" way of changing a
variable. They save one machine instruction, which can be important
if these operations occur in large time-critical loops.
Sometimes you will see code like
a = b * c++;
...which will NOT give the same result as
a = b * ++c;
...because in the first case, the ++ operator increments c AFTER the
value of c is used in the formula, and in the second case, the ++
operator increments c BEFORE it is used in the formula.
Also you will occasionally see a formula used within another formula,
like:
z = x + (a *= ++c) / (b = 2);
...which would require four separate statements in EL:
b = 2;
c = c + 1;
a = a * c;
z = x + a / b;
Confused now?
--
,|___ Alex Matulich -- alex@xxxxxxxxxxxxxx
// +__> Director of Research and Development
// \
// __) Unicorn Research Corporation -- http://unicorn.us.com
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