+= 实质
int x = 4;
long y = 3;
x = x + y;//报错
x = (int)(x+y);
x += y;// 相当于 x = (int)(x+y);
++i and i++
public class JavaP {
public static void main(String[] args) {
int i = 0;
i++;
int a = 0;
int b = a++;// b = 0, a = 1
int c = ++a;//c = 2, a = 2
System.out.println("i: "+i);//1
i = i++;
i = i++;
i = i++;
i = i++;
System.out.println("i: "+i);//1
for (int j = 0; j < 10; j++) {
System.out.print(j+" ");//0 1 2 3 4 5 6 7 8 9
}
System.out.println();
for (int j = 0; j < 10; ++j) {
System.out.print(j+" ");//0 1 2 3 4 5 6 7 8 9
}
}
i++和++i单独使用没有区别，但是赋值时就有区别了。- 当
int i = i++时，i 先赋值后加一。 - 当
int i = ++i时，i 先加一后赋值。
