Added post-test/pre-test loop example in Loops folder

Loops/postTest_preTest.cpp

@@ -0,0 +1,28 @@
+// Difference between a post-test and a pre-test loop.
+
+#include <iostream>
+using namespace std;
+
+int main(){
+    int myNum = 1;
+
+    cout << "Pre-test loop (TRUE): \n";
+    while (myNum <= 5){     // This block will be executed
+        cout << myNum << endl;
+        myNum++;    
+    }
+
+    cout << "\nPre-test loop (FALSE): \n";
+    myNum = 1;
+    while (myNum > 10){     // This loop will NOT be executed
+        cout << "Larger than 10.";
+        myNum--;
+    }
+
+    do {
+        cout << "\n\nPost-test loop. Print this at least once no matter what.\n\n";
+        myNum--;
+    } while (myNum > 0);
+
+    return 0;
+}