Finished exercises 2-7 and 2-8

ch_02/exercise_02-08/main.c

@@ -0,0 +1,53 @@
+/*
+ *
+ * Exercise 2-8. Write a function rightrot(x,n) that returns the value of the integer x
+ * rotated to the right by n positions.
+ *
+ * Author: Kun Deng
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+
+
+// Returns the value of the integer x rotated to the right by n positions
+unsigned int rightrot(unsigned int x, int n);
+
+
+int main(int argc, char **argv)
+{
+    unsigned int x = 511;
+    int n = 3;
+
+    if (argc == 3)
+    {
+        x = atoi(argv[1]);
+        n = atoi(argv[2]);
+    }
+
+    unsigned int rotated = rightrot(x, n);
+
+    printf("rightrot(%d, %d)", x, n);
+    printf(" = %u\n", rotated);
+
+    return 0;
+}
+
+
+unsigned int rightrot(unsigned int x, int n)
+{
+    unsigned int some_bits = CHAR_BIT * sizeof(x) - 1;
+    printf("size of x is %ld some_bits = %d\n", sizeof(x), some_bits);
+
+    unsigned int off = n & some_bits;
+    printf("off is %d\n", off);
+
+    printf("(%d >> %d) | (%d << (%d & %d))\n", x, off, x, off, some_bits);
+    printf("(%d >> %d) | (%d << %d)\n", x, off, x, (off && some_bits));
+    printf("%d | %d\n", (x >> off), (x << (off && some_bits)));
+
+    unsigned int rotated = (x >> off) | (x << (off & some_bits));
+
+    return rotated;
+}