A breakpoint is set on an executable line of a program. If the breakpoint is enabled when you debug, the execution suspends before that line of code executes.
To add a breakpoint:
A dot is
displayed in the marker bar and
in the Breakpoints view, along with the name of the associated file.
For more information on marker bar icons, see Workbench User Guide > Reference > User interface information > Icons and buttons > Editor area marker bar.
C/C++ Development perspective
Projects
Working with breakpoints and watchpoints