累加求和，累加求阶乘2\c1.c
.....................\c1.dsp
.....................\c1.dsw
.....................\c1.ncb
.....................\c1.opt
.....................\c1.plg
.....................\Debug\c1.exe
.....................\.....\c1.ilk
.....................\.....\c1.obj
.....................\.....\c1.pch
.....................\.....\c1.pdb
.....................\.....\vc60.idb
.....................\.....\vc60.pdb
.....................\Debug
累加求和，累加求阶乘2