Debugging a Program With dbx

Tracing Code

Tracing displays information about the line of code about to be executed or a function about to be called.

Setting a Trace

Set a trace by typing a trace command at the command line. Table 5-1 shows the command syntax for the types of traces that you can set. The information a trace provides depends on the type of event associated with it.

Table 5-1 trace Command Syntax


Command	`trace` prints ...
`trace step`	Every line in the program as it is about to be executed
`trace next` -`in` `function`	Every line while the program is in the function
`trace at` `line_number`	The line number and the line itself, as that line becomes the next line to be executed
`trace in` `function`	The name of the function that called `function`; line number, parameters passed in, and return value
`trace inmember` `member_function`	The name of the function that called `member_function` of any class; its line number, parameters passed in, and its return value
`trace inclass` `class`	The name of the function that called any member_function in `class`; its line number, parameters passed in, and return value
`trace infunction` `function`	The name of the function that called any member_function in `class`; its line number, parameters passed in, and return value
`trace change` `variable` `[-in` `function]`	The new value of `variable`, if it changes, and the line at which it changed

Controlling the Speed of a Trace

In many programs, code execution is too fast to view the code. The dbxenv trace_speed allows you to control the delay after each trace is printed. The default delay is 0.5 seconds.

To set the interval between execution of each line of code during a trace:

dbxenv trace_speed number