C語言_常見位操作

---

一、位操作函數

設置某位為1或者對某位清0、獲取某位的值、對某位取反

/*對某位置1*/
unsigned Setbit(unsigned x,int n)
{return  x |= 1 << n;
}/*對某位清0*/
unsigned Resetbit(unsigned x,int n)
{return  x &= ~(1 << n);
}/*取某位的值*/
unsigned Getbit(unsigned x,int n)
{return  ((x) >> (n)&1))
}/*對某位取反*/
unsigned Invertbit(unsigned x,int n)
{return   ((x) ^= 1<<(n))
}

獲取x從p位到n位的值

unsigned Getbits(unsigned x,int p,int n)
{return (x >> (p+1-n)) & ~(~0 << n);
}

設置x從p位到n位的值

unsigned Setbits(unsigned x,int p,int n,int y)
{return x & ~(~(~0 << n) << (p+1-n)) | (y & ~(~0 << n)) << (p+1-n);
}

對x從p位到n位的值進行取反

unsigned Invertbits(unsigned x,int p,int n)
{return x ^ (~(~0 << n)) << (p-n+1);
}

對x循環右移n位

unsigned Rightbits(unsigned x,int n)
{return (x >> n) | (x << (8*(sizeof(unsigned))-n));
}

二、代碼示例

代碼如下（示例）：

#include<stdio.h>
#include<string.h>void print_binary(unsigned int num) {if (num > 1) {print_binary(num >> 1);}putchar((num & 1) ? '1' : '0');}/*對某位置1*/
unsigned Setbit(unsigned x,int n)
{return  x |= 1 << n;
}/*對某位清0*/
unsigned Resetbit(unsigned x,int n)
{return  x &= ~(1 << n);
}/*取某位的值*/
unsigned Getbit(unsigned x,int n)
{return  ((x) >> (n)&1);
}/*對某位取反*/
unsigned Invertbit(unsigned x,int n)
{return   ((x) ^= 1<<(n));
}unsigned Getbits(unsigned x,int p,int n)
{return (x >> (p+1-n)) & ~(~0 << n);
}unsigned Setbits(unsigned x,int p,int n,int y)
{return x & ~(~(~0 << n) << (p+1-n)) | (y & ~(~0 << n)) << (p+1-n);
}unsigned Invertbits(unsigned x,int p,int n)
{return x ^ (~(~0 << n)) << (p-n+1);
}unsigned Rightbits(unsigned x,int n)
{return (x >> n) | (x << (8*(sizeof(unsigned))-n));
}void main(int argc,char* argv[])
{int a= 178 ,b= 178 , c= 178 , d= 178 , e= 178 , f= 178 , g= 178 , h = 178;  int p = 5,n = 3;printf(" 178: \t\t\t");print_binary(a);printf("\t\n\n");printf(" Setbit(a,3): \t\t");print_binary(Setbit(a,3));printf("\t\n");printf(" Resetbit(b,4): \t");print_binary(Resetbit(b,4));printf("\t\n");printf(" Getbit(c,5):\t\t");print_binary(Getbit(c,5));printf("\t\n");printf(" Invertbit(d,2):\t");print_binary(Invertbit(d,2));printf("\t\n");printf(" Getbits(e,5,3):\t");print_binary(Getbits(e,5,3));printf("\t\n");printf(" Setbits(f,p,n,15):\t");print_binary(Setbits(f,p,n,15));printf("\t\n");printf(" Invertbits(g,5,3):\t");print_binary(Invertbits(g,5,3));printf("\t\n");printf(" Rightbits(h,5):\t");print_binary(Rightbits(h,5));printf("\t\n");}

結果：
178:??????? 10110010
Setbit(a,3):???? 10111010
Resetbit(b,4):??? 10100010
Getbit(c,5):???? 1
Invertbit(d,2):??? 10110110
Getbits(e,5,3):???110
Setbits(f,p,n,15):??10111010
Invertbits(g,5,3):??10001010
Rightbits(h,5):???10010000000000000000000000000101

---