Merge pull request #119 from dynamsoft-docs/preview

update to internal commit 465cb463

Author: DMGithubPublisher

programming/cplusplus/user-guide.md

@@ -135,6 +135,8 @@ else
 ### Release the Allocated Memory
 
 ```cpp
+if (barcodeResult)
+    barcodeResult->Release();
 result->Release();
 delete cvr, cvr = NULL;
 ```