### 13.4 Debug Mode ¶

There are three additional support functions that allow the user to find out 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.

dbwhere ¶

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

  See also: dbstack, dblist, dbstatus, dbcont, dbstep, dbup, dbdown.

dbtype ¶
dbtype `lineno` ¶
dbtype `startl:endl` ¶
dbtype `startl:end` ¶
dbtype `fcn` ¶
dbtype `fcn lineno` ¶
dbtype `fcn startl:endl` ¶
dbtype `fcn 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: dblist, dbwhere, dbstatus, dbstop.

dblist ¶
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, dbstack.

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

`tf =` 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`.

dbstep ¶
dbstep `n` ¶
dbstep `in` ¶
dbstep `out` ¶
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.

  Programming Note: `dbnext` is an alias for `dbstep` and can be used interchangeably.

  See also: dbcont, dbquit.

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

`val =` auto_repeat_debug_command `()` ¶
`old_val =` auto_repeat_debug_command `(new_val)` ¶
`old_val =` auto_repeat_debug_command `(new_val, "local")` ¶

  Query or set the internal variable that controls whether debugging commands are automatically repeated when the input line is empty (typing just `RET`).

  When called from inside a function with the `"local"` option, the variable is changed locally for the function and any subroutines it calls. The original variable value is restored when exiting the function.