《C程序设计语言》练习 2-8

int rightrot(int x, int n)
{
int b, c;
c = ~0U >> 1;
while (n > 0)
{
b = x & 1;
x = x >> 1;
if (b)
x = x | ~c;
else
x = x & c;
n--;
}
return x;
}

#include <stdio.h>

int rightrot(int x, int n);
void printBirany(int x, int bit);

main()
{
int x = 123;
x = rightrot(x, 5);
printf("%d\n", x);
}

int rightrot(int x, int n)
{
//printBirany(x, 32);

int b, c;
c = ~0U >> 1; // 0x80000000 最左位是0，其他的是1
while (n > 0)
{
//保存位移前最右的值
b = x & 1;
x = x >> 1;

//根据位移前最右的值，改变位移后最左
if (b)
x = x | ~c;
else
x = x & c;
n--;

//printBirany(x, 32);
}
return x;
}
void printBirany(int x, int bit)
{
int i;
for (i = 0; i < bit; i++)
{
printf("%d", (x >> (bit - i - 1) & 1));
if ((i + 1) % 4 == 0)
putchar(' ');
}
printf("\n");
}