Accessing Local Variables

Local variables, like global variables, are stored in the symbol files. And as with global variables, the debugger interprets their names as addresses. They can be read and written in the same manner as global variables. However, if you need to indicate to a command that a symbol is local, precede the symbol with a dollar sign ( $ ) and an exclamation point ( ! ), as in $!var.

Visual Studio and WinDbg provide user interface elements that you can use (in addition to commands) to view and edit local variables. For more information, see Viewing and Editing Local Variables in WinDbg (Classic).

You can also use the following methods to display, change, and use local variables:

• The dv (Display Local Variables) command displays the names and values of all local variables.

• The !for_each_local extension enables you to execute a single command repeatedly, once for each local variable.

However, there is one primary difference between local and global variables. When an application is executing, the meaning of local variables depends on the location of the program counter, because the scope of such variables extends only to the function in which they are defined.

The debugger interprets local variables according to the local context. By default, this context matches the location of the program counter. But the debugger can change the context. For more information about the local context, see Local Context.

When the local context is changed, the Locals window is immediately updated to reflect the new collection of local variables. The dv command also shows the new variables. All of these variable names are then interpreted correctly by the memory commands that are described earlier. You can then read or write to these variables.