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13.4 Debug Mode

There are three additional support functions that allow the user to interrogate where in the execution of a script Octave entered the debug mode and to print the code in the script surrounding the point where Octave entered debug mode.

Command: dbwhere

In debugging mode, report the current file and line number where execution is stopped.

See also: dbstatus, dbcont, dbstep, dbup.

Command: dbtype
Command: dbtype lineno
Command: dbtype startl:endl
Command: dbtype startl:end
Command: dbtype func
Command: dbtype func lineno
Command: dbtype func startl:endl
Command: dbtype func startl:end

Display a script file with line numbers.

When called with no arguments in debugging mode, display the script file currently being debugged. An optional range specification can be used to list only a portion of the file. The special keyword "end" is a valid line number specification for the last line of the file.

When called with the name of a function, list that script file with line numbers.

See also: dbwhere, dbstatus, dbstop.

Command: dblist
Command: dblist n

In debugging mode, list n lines of the function being debugged centered around the current line to be executed. If unspecified n defaults to 10 (+/- 5 lines)

See also: dbwhere, dbtype.

You may also use isdebugmode to determine whether the debugger is currently active.

Built-in Function: isdebugmode ()

Return true if in debugging mode, otherwise false.

See also: dbwhere, dbstack, dbstatus.

Debug mode also allows single line stepping through a function using the command dbstep.

Command: dbstep
Command: dbstep n
Command: dbstep in
Command: dbstep out
Command: dbnext

In debugging mode, execute the next n lines of code. If n is omitted, execute the next single line of code. If the next line of code is itself defined in terms of an m-file remain in the existing function.

Using dbstep in will cause execution of the next line to step into any m-files defined on the next line. Using dbstep out will cause execution to continue until the current function returns.

dbnext is an alias for dbstep.

See also: dbcont, dbquit.

When in debug mode the RETURN will execute the last entered command. This is useful, for example, after hitting a breakpoint and entering dbstep. After that one can advance line by line through the code with only a single key stroke.


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