Commands That Alter the State of the Program

assign

The dbx assign command assigns a value of the exp to var. Using it in dbx permanently alters the value of var.

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assign var = exp

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pop

The dbx pop command pops a frame or frames from the stack:

Pop current frame	pop
Pop num frames	pop num
Pop frames until specified frame number	pop -f num

Any calls popped are re-executed upon resumption, which may result in undesirable program changes. pop also calls destructors for objects local to the popped functions.

call

When you use the call command in dbx you call a procedure, and the procedure performs as specified:

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call proc([params]) 

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The procedure could modify something in your program. dbx is actually making the call as if you had written it into your program source.

print

To print the value of the expression(s):

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print exp, ... 

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If an expression has a function call, the same considerations apply as with the call command. With C++, you should also be careful of unexpected side effects caused by overloaded operators.

when

The when command has a general syntax as follows:

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when event-specification
 [modifier]
{cmd ... ;}

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When the event occurs, the cmds are executed.

When you get to a line or to a procedure, a command is performed. Depending upon which command is issued, this could alter your program state.

fix

You can use fix to make on-the-fly changes to your program:

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fix

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It is a very useful tool, but remember that fix recompiles modified source files and dynamically links the modified functions into the application.

Make sure to check the restrictions for fix and continue. See Chapter 11, Fixing and Continuing."

cont at

This dbx command alters the order in which the program runs. Execution is continued at line line. id is required if the program is multithreaded.

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cont at line id

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This could change the outcome of the program.