CDE

Task/Exponentiation-operator/C/exponentiation-operator.c

@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <assert.h>
+
+int ipow(int base, int exp)
+{
+   int pow = base;
+   int v = 1;
+   if (exp < 0) {
+      assert (base != 0);  /* divide by zero */
+      return (base*base != 1)? 0: (exp&1)? base : 1;
+   }
+
+   while(exp > 0 )
+   {
+      if (exp & 1) v *= pow;
+      pow *= pow;
+      exp >>= 1;
+    }
+   return v;
+}
+
+double dpow(double base, int exp)
+{
+   double v=1.0;
+   double pow = (exp <0)? 1.0/base : base;
+   if (exp < 0) exp = - exp;
+
+   while(exp > 0 )
+   {
+      if (exp & 1) v *= pow;
+      pow *= pow;
+      exp >>= 1;
+   }
+   return v;
+}
+
+int main()
+{
+    printf("2^6 = %d\n", (int)ipow(2,6));
+    printf("2^-6 = %lf\n", ipow(2,-6));
+    printf("2.71^6 = %lf\n", dpow(2.71,6));
+    printf("2.71^-6 = %lf\n", dpow(2.71,-6));
+}