位运算...

Posted 2020-09-18 ioioioioioio

 1 //5.13晚 位运算
 2 
 3 1. int 类型最大值
 4 
 5 int Getmaxint()
 6 {
 7     return (1<<31)-1;//2147483647
 8 } 
 9 
10 int Getmaxint()
11 {
12     return ~(1<<31);
13 }
14 
15 2. int 所占字节
16 
17 int Getzjint()
18 {
19     return ((unsigned int)-1)>>1;//-2147483648    
20 } 
21 
22 3. n/2
23 
24 n>>1;
25 
26 4. n*2
27 
28 n<<1;
29 
30 5. n*(2^m)
31 
32 n>>m;
33 
34 6. n/(2*m)
35 
36 n>>m;
37 
38 7. swap(a,b)
39 
40 a^=b;
41 b^=a;
42 a^=b;
43 
44 8. 2^n
45 
46 2<<(n-1);//最多算到2^30
47 
48 9. 对2^n%
49 
50 int m,int n,
51 2^n%m
52 
53 m&(n-1);