原文链接：Bitwise Operation Explained
1.统计一个数置位为1的个数
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#include <stdio.h>
int __numOf_SET_Bits(int var)
{
if (var==0) return 0;
else return (var&01)?1+__numOf_SET_Bits(var>>1):__numOf_SET_Bits(var>>1);
}
int main()
{
int var=128;
printf("Num of Bits: %d\n",__numOf_SET_Bits(var));
return 0;
}
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2,判断一个数是奇数还是偶数
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#include <stdio.h>
#define isEven(a) ((((a)&01)==0)?1:0)
int main()
{
int var=1;
if(isEven(var))
{
printf("%d is a even number \n",var);
}
else
printf("%d is a odd number \n",var);
return 0;
}
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方法二：
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#include <stdio.h>
#define isEven(a) ((((a)%2)==0)?1:0)
int main()
{
int var=11;
if(isEven(var))
{
printf("%d is a even number \n",var);
}
else
printf("%d is a odd number \n",var);
return 0;
}
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3，判断一个数是否是2的幂次方
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#include <stdio.h>
#define __isPower_of_TWO(a) (((a)&(a-1))==0)?1:0
int main()
{
int arr[] = {1,2,3,4,5,8,9,16};
int i=0;
for(;i<sizeof(arr)/sizeof(arr[0]);i++)
{
if (__isPower_of_TWO(*(arr+i)))
printf("%d has a form of Power of Two \n",*(arr+i));
else
printf("%d is not in the form \n", *(arr+i));
}
return 0;
}
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方法二：
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#include <stdio.h>
#define __isPower_of_TWO(a) (((a)&(-a))==a)?1:0
int main()
{
int arr[] = {1,2,3,4,5,8,9,16};
int i=0;
for(;i<sizeof(arr)/sizeof(arr[0]);i++)
{
if (__isPower_of_TWO(*(arr+i)))
printf("%d has a form of Power of Two \n",*(arr+i));
else
printf("%d is not in the form \n", *(arr+i));
}
return 0;
}
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方法三：
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#include <stdio.h>
#include <stdlib.h>
int __numOf_SET_Bits(int var)
{
if (var==0) return 0;
else return (var&01)?1+__numOf_SET_Bits(var>>1):__numOf_SET_Bits(var>>1);
}
int main()
{
int arr[] = {1,2,3,4,5,8,9,16};
int i=0;
for(;i<sizeof(arr)/sizeof(arr[0]);i++)
{
if (__numOf_SET_Bits(arr[i])==1)
printf("%d has a form of Power of Two \n",*(arr+i));
else
printf("%d is not in the form \n", *(arr+i));
}
system("pause");
return 0;
}
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4，不使用第三个数，交换两个数
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#include <stdio.h>
void __SWAP(int *a,int *b)
{
*a = *a ^ *b;
*b = *a ^ *b;
*a = *a ^ *b;
}
int main()
{
int a=5, b=6;
printf("Before swap: a=%d <=====> b=%d \n",a,b);
__SWAP(&a,&b);
printf("After swap: a=%d <=====> b=%d \n",a,b);
return 0;
}
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5，异或双向链表
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#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
typedef struct XOR_based_Node
{
int data;//数据域
unsigned long compressedAddress;
}node;
node* head = NULL;//异或双向链表表头
void add_element_to_list(node** headRef, int data)
{//插入表头
node *newNode = (node*)malloc(sizeof(node));
assert(newNode);
newNode->compressedAddress = (unsigned long)(*headRef);
newNode->data = data;
if(*headRef != NULL)
(*headRef)->compressedAddress ^= (unsigned long)newNode;
*headRef=newNode;
}
void printList(node* head)
{//输出表
unsigned long prev = 0;
while(head)
{
unsigned long next = prev ^ head->compressedAddress;
printf("%d ", head->data);
prev = (unsigned long)head;
head = (node *)next;
}
printf("\n");
}
int main(void)
{
int i=0;
for(;i<10;i++)
add_element_to_list(&head,i);
printList(head);
return 0;
}
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本文转自Phinecos(洞庭散人)博客园博客，原文链接：http://www.cnblogs.com/phinecos/archive/2008/08/22/1273784.html，如需转载请自行联系原作者
