问题
Possible Duplicate:
What is the difference between ++i and i++
pre Decrement vs. post Decrement
Yes I'm a noob, but I completely forgot what they both do.
I know, however, that int++ just adds one to the value of int.
So, what is ++int?
Thank you.
回答1:
If you're talking about C (or C-like languages), it's exactly the same unless you use the value:
int a = 10;
int b = a++;
In that case, a becomes 11 and b is set to 10. That's post-increment - you increment after use.
If you change that line above to:
int b = ++a;
then a still becomes 11 but so does b. That's because it's pre-increment - you increment before use.
Note that it's not quite the same thing for C++ classes, there are efficiencies that can be had by preferring one over the other. But since you're talking about integers, C++ acts the same as C.
回答2:
a++ will return a and increment it, ++a will increment a and return it:
a = 5;
b = a++; // b = 5, a = 6
a = 5;
b = ++a; // b = 6, a = 6
回答3:
Every expression in C or C++ has a type, a value, and possible side-effects.
int i;
++i;
The type of ++i is int. The side-effect is to increment i. The value of the expression is the new value of i.
int i;
i++;
The type of i++ is int. The side-effect is to increment i. The value of the expression is the old value of i.
回答4:
it's the preincrement operator
nice explanation here
来源：https://stackoverflow.com/questions/9917564/what-is-the-difference-between-int-and-int