Single stepping offers an alternative to setting breakpoints. It allows you to trace the flow of execution a single line at a time. There are two possible methods of single stepping, step into and step over.
The first method (step into) will enter any function or subroutine which contains debugging information. This is useful when you want to follow the logical flow through several routines. You can use the step into method by pressing F7. If you step into a new subroutine or function a new source window will be opened. This will display the code for the new subroutine/function. Alternatively, if you execute a return statement, the current source window will be closed and the window with the calling line will be made the current window.
The second method (step over) will execute the current line but will not enter a subroutine or function even if debugging information is present. This latter case is useful when you are sure that a subroutine or function is working correctly and you do not want to trace the call through the routine. Whilst a new window will never be opened with the step over method, it is possible for the current source window to close due to the execution of a return statement. The step over method is performed by pressing F8.