diff --git a/examples/helloworld.cc b/examples/helloworld.cc
index 22dff55..9e32fad 100644
--- a/examples/helloworld.cc
+++ b/examples/helloworld.cc
@@ -39,15 +39,16 @@
 using ceres::AutoDiffCostFunction;
 using ceres::CostFunction;
 using ceres::Problem;
-using ceres::Solver;
 using ceres::Solve;
+using ceres::Solver;
 
 // A templated cost functor that implements the residual r = 10 -
 // x. The method operator() is templated so that we can then use an
 // automatic differentiation wrapper around it to generate its
 // derivatives.
 struct CostFunctor {
-  template <typename T> bool operator()(const T* const x, T* residual) const {
+  template <typename T>
+  bool operator()(const T* const x, T* residual) const {
     residual[0] = 10.0 - x[0];
     return true;
   }
@@ -68,7 +69,7 @@
   // auto-differentiation to obtain the derivative (jacobian).
   CostFunction* cost_function =
       new AutoDiffCostFunction<CostFunctor, 1, 1>(new CostFunctor);
-  problem.AddResidualBlock(cost_function, NULL, &x);
+  problem.AddResidualBlock(cost_function, nullptr, &x);
 
   // Run the solver!
   Solver::Options options;
@@ -77,7 +78,6 @@
   Solve(options, &problem, &summary);
 
   std::cout << summary.BriefReport() << "\n";
-  std::cout << "x : " << initial_x
-            << " -> " << x << "\n";
+  std::cout << "x : " << initial_x << " -> " << x << "\n";
   return 0;
 }