The C/C++ indexer is on by default. You can enable/disable indexing on any project from the C/C++ perspective.
The indexer can be enabled or disabled at any time by:
If you enable the index on a project that had the index disabled, the indexer will reindex all of the project’s source folders.
If you disable the index on a project, it will no longer react to any resource change events. If the indexer is indexing at the time you disable the index, it will throw away the rest of the index jobs at that point.
If some projects in your workspace have the indexer disabled, then search will display a warning message in the status bar. If all projects have the index disabled then Search will not allow you to continue until at least one project has the index enabled.
You can also disable the indexer when you first create a new project by clicking on the C/C++ Indexer tab (which is present in both Standard and Managed project wizards) and deselecting the Enable C/C++ Indexing checkbox.
C/C++ search
C/C++ Indexer
C/C++ Indexer Problem Reporting
C/C++ Indexer Opening or Closing a project
C/C++ Indexer Progress Bar
Selection Searching for C/C++ elements
C/C++ Indexer Problem Reporting
C/C++ Indexer - Indexer Timeout
Setting Source Folders
Search, C/C++ Preferences window
C/C++ search page, Search dialog box
C/C++ Project Properties, Managed, Indexer
C/C++ Project Properties, Standard, Indexer