Overview of Data Visualization

You can visualize either variables (including arrays, structures, pointers, etc.) or expressions; see " Writing Expressions in Prism" for information about writing expressions in Prism. In addition, you can provide a context, so that Prism handles the values of data elements differently, depending on whether they meet the condition you specify.

Printing and Displaying

Prism provides two general methods for visualizing data: printing and displaying.

• Printing data shows the value(s) of the data at a specified point during program execution.

• Displaying data causes its value(s) to be updated every time the program stops execution.

Printing or displaying to the history region of the command window prints out the numeric or character values of the data in standard fashion.

Printing or displaying to a graphical window creates a visualizer, which provides you with various options as to how to represent the data.

Visualization Methods

Prism provides these methods for choosing what to print or display:

• By choosing the Print or Display selection from the Debug menu in the menu bar (see " Printing and Displaying From the Debug Menu")

• By selecting text within the source window (see " Printing and Displaying From the Source Window")

• By adding events to the Event Table (see "Printing and Displaying From the Event Table")

• By issuing commands from the command window (see " Printing and Displaying From the Command Window")

In all cases, choosing Display adds an event to the event list, since displaying data requires an action to update the values each time the program is stopped. Note that, since Display updates automatically, the only way to keep an unwanted display window from reappearing is to delete the corresponding display event.

You create print events only via the Event Table and the Events menu.

Changing the Default Radix

By default, Prism prints and displays values as decimal numbers. You can change this default by issuing the set $radix command, specifying as a setting 2 (binary), 8 (octal), or 16 (hexadecimal). For example,

set $radix = 16

changes the default representation to hexadecimal. To reset the default to decimal, issue the command

set $radix = 10

You can override the default for an individual print or display operation. See " Printing and Displaying From the Command Window" and " Using the Options Menu".

The default setting also affects the display of argument values in procedures in the call stack; see " Displaying the Call Stack".

Data Visualization Limits

Note these points in visualizing data:

• You cannot print or display any variables after a program finishes execution.

• Visualizers do not deal correctly with Fortran adjustable arrays. The size is determined when you create a visualizer for such an array. Subsequent updates to the visualizer will continue to use this same information, even though the size of the array may have changed since the last update. This will result in incorrect values in the visualizer. Printing or displaying values of an adjustable array in the command window or to a new window will work, however.