Swap. Completed MPIR 2.6.0 section 5.2, except setting MPZ from MPQ or MPF

build.vc11/mpir.net/mpir.net-tests/HugeIntTests/Assignment.cs

@@ -35,6 +35,20 @@ namespace MPIR.Tests.HugeIntTests
                 Assert.AreEqual("-222509832503450298345029835740293845720", b.ToString());
             }
         }
+
+        [TestMethod]
+        public void Swap()
+        {
+            using (var a = new HugeInt("-222509832503450298345029835740293845720"))
+            using (var b = new HugeInt("2039847290878794872059384789347534534"))
+            {
+                var aValue = a._value();
+                var bValue = b._value();
+                a.Swap(b);
+                Assert.AreEqual(bValue, a._value());
+                Assert.AreEqual(aValue, b._value());
+            }
+        }
         //more tests coming here
     }
 }

build.vc11/mpir.net/mpir.net/HugeInt.h

@@ -367,5 +367,8 @@ namespace MPIR
             void SetTo(double value) { mpz_set_d(_value, value); }
             void SetTo(String^ value) { SetTo(value, 10); }
             void SetTo(String^ value, int base);
+
+            //utility methods
+            void Swap(HugeInt^ a) { mpz_ptr temp = a->_value; a->_value = _value; _value = temp; }
     };
 };