In programming, particularly in Java, what is the difference between:
int var = 0;
var++;
and
int var = 0;
++var;
What repercussions would this have on a for loop?
e.g.
for (int i = 0; i < 10; i++) {}
for (int i = 0; i < 10; ++i) {}
Although both var++
and ++var
increment the variable they are applied to, the result returned by var++
is the value of the variable before incrementing, whereas the result returned by ++var
is the value of the variable after the increment is applied.
When ++var
or var++
form a complete statement (as in your examples) there is no difference between the two. For example the following
int x = 6;
++x;
assert x == 7;
is identical to
int x = 6;
x++;
assert x == 7;
However, when ++var
or var++
are used as part of a larger statement, the two may not be equivalent. For example, the following assertion passes
int x = 6;
assert ++x == 7;
whereas this one fails
int x = 6;
assert x++ == 7;
Although both var++
and ++var
increment the variable they are applied to, the result returned by var++
is the value of the variable before incrementing, whereas the result returned by ++var
is the value of the variable after the increment is applied.
When used in a for
loop, there is no difference between the two because the incrementation of the variable does not form part of a larger statement. It may not appear this way, because there is other code on the same line of the source file. But if you look closely, you'll see there is a ;
immediately before the increment and nothing afterwards, so the increment operator does not form part of a larger statement.