41.5. Watch Windows

Earlier in this chapter you saw how datatips can be used in the code window to examine the content of a variable by hovering the mouse over a variable name. When the structure of the object is more complex it becomes difficult to navigate the values using just the datatip. Visual Studio 2008 has a series of watch windows that can be used to display variables, providing an easy-to-use interface for drilling down into the structure.

41.5.1. QuickWatch

The QuickWatch window is a modal dialog that can be launched by right-clicking on the code window. Whatever you have selected in the code window is inserted into the Expression field of the dialog, as shown in Figure 41-6 where a Customer object is visible. Previous expressions you have evaluated appear in the drop-down associated with the Expression field.

Figure 41.6. Figure 41-6

The layout of the Value tree in the QuickWatch window is similar to the datatip, without the annoyance of its disappearing. Each row shows the variable name, the current value, and the type of object. The value of the variable can be adjusted by typing in the Value column.

Use the Add Watch button to add the current expression to one of the watch windows. These are variables to be continuously watched.

41.5.2. Watch Windows 1–4

Unlike the QuickWatch window, which is modal and shows a variable value at a particular execution point, the watch windows can be used to monitor a variable value as you step through your code. Although there are four watch windows, a single window is sufficient in most cases. Having four separate windows means that you can have different sets of variables in the different windows, which might be useful if you are working through a more complex issue that involves multiple classes.

Figure 41-7 shows an Order and Customer class in a watch window. Similar to both the QuickWatch window and the datatips discussed previously, the user interface can be used to drill down into more complex data types.

Figure 41.7. Figure 41-7

Additional variables to be watched can be added either by typing into the Name column on an empty line or by right-clicking the variable in the code window and selecting Add Watch from the context menu.

41.5.3. Autos and Locals

The Autos and Locals windows are two special watch windows in which the variables are automatically added by the debugger. The Autos window contains variables that are used in the current, preceding, and future lines of code. Similarly, the Locals window shows all variables used in the current method. Other than being automatically generated, these windows behave the same as the watch windows.