examples: Remove heap allocation from C++ examples

Cleanup of UPM C++ examples.  Switched from heap allocation to
stack allocation when possible.  This simplifies the samples since it
removes the need for explicit memory management.  A script was used to
identify and replace pointer use.  To simplify the replace script, I
re-formatted the C++ examples using the UPM .clang-format file.
Unfortuantely this changes the look of the UPM C++ examples to a large
degree.  However, examples will now have a standard look/feel and
uniform formatting.

    * Ran clang-format w/provided UPM .clang-format file
    * Removed new's/delete's whenever possible (left those in interface
      examples)
    * Added IIO sensor library implementation of callback void* arg
    * Converted all sleeps to upm defined delays (added header when
      necessary)
    * Scrubbed CXX example includes

Signed-off-by: Noel Eck <noel.eck@intel.com>

examples/c++/gas-mq6.cxx

@@ -22,12 +22,12 @@
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
-#include <unistd.h>
 #include <iostream>
-#include "mq6.hpp"
 #include <signal.h>
-#include <stdlib.h>
-#include <sys/time.h>
+#include <stdint.h>
+
+#include "gas.hpp"
+#include "mq6.hpp"
 
 bool shouldRun = true;
 
@@ -36,46 +36,43 @@ using namespace std;
 void
 sig_handler(int signo)
 {
-  if (signo == SIGINT) 
-    {
-      shouldRun = false;
+    if (signo == SIGINT) {
+        shouldRun = false;
     }
 }
 
 //! [Interesting]
-int main(int argc, char **argv)
+int
+main(int argc, char** argv)
 {
-  // Attach gas sensor to Analog A0
-  upm::MQ6 *sensor = new upm::MQ6(0);
-  signal(SIGINT, sig_handler);
-  
-  uint16_t buffer [128];
+    // Attach gas sensor to Analog A0
+    upm::MQ6 sensor(0);
+    signal(SIGINT, sig_handler);
 
-  thresholdContext ctx;
-  ctx.averageReading = 0;
-  ctx.runningAverage = 0;
-  ctx.averagedOver   = 2;
-  
-  // Infinite loop, ends when script is cancelled
-  // Repeatedly, take a sample every 2 microseconds;
-  // find the average of 128 samples; and
-  // print a running graph of asteriskss as averages
-  while (shouldRun) 
-    {
-      int len = sensor->getSampledWindow (2, 128, buffer);
-      if (len) {
-        int thresh = sensor->findThreshold (&ctx, 30, buffer, len);
-        sensor->printGraph(&ctx, 5);
-        if (thresh) {
-          // do something ....
+    uint16_t buffer[128];
+
+    thresholdContext ctx;
+    ctx.averageReading = 0;
+    ctx.runningAverage = 0;
+    ctx.averagedOver = 2;
+
+    // Infinite loop, ends when script is cancelled
+    // Repeatedly, take a sample every 2 microseconds;
+    // find the average of 128 samples; and
+    // print a running graph of asteriskss as averages
+    while (shouldRun) {
+        int len = sensor.getSampledWindow(2, 128, buffer);
+        if (len) {
+            int thresh = sensor.findThreshold(&ctx, 30, buffer, len);
+            sensor.printGraph(&ctx, 5);
+            if (thresh) {
+                // do something ....
+            }
         }
-      }
     }
-  
-  cout << "Exiting" << endl;
-  
-  delete sensor;
-  
-  return 0;
+
+    cout << "Exiting" << endl;
+
+    return 0;
 }
 //! [Interesting]