"Start Debugging" and "Start without Debugging"

When you start with debugging it allows you to add break points and step through the code as it will load the debugging symbols.

If you start without debugging then the symbols dont get loaded so you can not step through the code with the break points, much like a release build. 

So,if you want to debug your program,you should choose"Start Debugging",the shortcut key is F5,then you can step through you program.
F5: 从一个断点执行到下一个断点
F9: 对光标所在的当前行设置断点
F10: 逐句执行，遇到子函数不进入
F11: 逐句执行，遇到子函数进入

If you want to see the result of you program,you should choose"Start without Debugging",the shortcut key is "ctrl+F5",then you can see the result,press a key in your keyboard,the program is over then.