32.6.5.4 Watch Expressions

If you want to see how a variable changes each time your program stops then place the cursor over the variable name and click on the watch icon in the tool bar (gud-watch).

Each watch expression is displayed in the speedbar. Complex data types, such as arrays, structures and unions are represented in a tree format. Leaves and simple data types show the name of the expression and its value, and display the type as a tooltip. Higher levels show the name, type and address value for pointers and just the name and type otherwise.

To expand or contract a complex data type, click Mouse-2 on the tag to the left of the expression.

With the cursor over the root expression of a complex data type, type D to delete it from the speedbar (gdb-var-delete).

With the cursor over a simple data type or an element of a complex data type which holds a value, type <RET> or click Mouse-2 to edit its value. A prompt for a new value appears in the mini-buffer (gdb-edit-value).

If you set the variable gdb-show-changed-values to non-nil (the default value), Emacs will use font-lock-warning-face to display values that have recently changed in the speedbar.

If you set the variable gdb-use-colon-colon-notation to a non-nil value then, in C, Emacs will use the function::variable format to display variables in the speedbar. Since this does not work for variables defined in compound statements, the default value is nil.