Debugging a Program With dbx

Continuing a Program

To continue a program, just use the cont command:


(dbx) cont

The cont command has a variant, cont at line_number, which allows you to specify a line other than the current program location line at which to resume program execution. This allows you to skip over one or more lines of code that you know are causing problems, without having to recompile.

To continue a program at a specified line, enter the cont at line_number command in the command pane:


(dbx) cont at 124

The line number is evaluated relative to the file in which the program is stopped; the line number given must be within the scope of the current function.

Using cont at line_number with assign, you can avoid executing a line of code that contains a call to a function that may be incorrectly computing the value of some variable.

To resume program execution at a specific line:

  1. Use assign to give the variable a correct value.

  2. Use cont at line_number to skip the line that contains the function call that would have computed the value incorrectly.

Assume that a program is stopped at line 123. Line 123 calls a function, how_fast() that computes incorrectly a variable, speed. You know what the value of speed should be, so you assign a value to speed. Then you continue program execution at line 124, skipping the call to how_fast().


(dbx) assign speed = 180; cont at 124;

If you use this command with a when breakpoint command, the program skips the call to how_fast() each time the program attempts to execute line 123.


(dbx) when at 123 { assign speed = 180; cont at 124;}