After you have stopped at a breakpoint, you might want to step through your program one source line at a time while you compare its actual state with the expected state. You can use the step and next commands to do so. Both commands execute one source line of your program, stopping when that line has completed execution. The commands handle source lines that contain function calls differently: the step command steps into the function, while the next command steps over the function.
The step up command continues execution until the current function returns control to the function that called it.
The step to command attempts to step into a specified function in the current source line, or if no function is specified, into the last function called as determined by the assembly code for the current source line.
Some functions, notably library functions such as printf, might not have been compiled with the -g option, so dbx cannot step into them. In such cases, step and next perform similarly.
The following example shows the use of the step and next commands as well as the breakpoint set in Setting Breakpoints.
(dbx) stop at 13
(3) stop at "t.c":13
(dbx) run
Running: a.out
stopped in main at line 13 in file "t.c"
13 printit(msg);
(dbx) next
Hello world
stopped in main at line 14 in file "t.c"
14 }
(dbx) run
Running: a.out
stopped in main at line 13 in file "t.c"
13 printit(msg);
(dbx) step
stopped in printit at line 6 in file "t.c"
6 printf("%s\n", msg);
(dbx) step up
Hello world
printit returns
stopped in main at line 13 in file "t.c"
13 printit(msg);
(dbx)For more information about stepping through your program, see Stepping Through a Program. For more information about the step and next commands, see step Command and next Command.