PPT7 VB控制结构解析.ppt
文本预览下载声明
采用Print直接在窗体上输出结果,程序代码: Private Sub Form_Load() Show t = 1 For c = 1 To 8 t = t * c Next c Print T=; t End Sub 程序运行结果是: T=40320语句t=t*c也称乘法器。先将t置1(不能置0)。在循环程序中,常用累加器和累乘器来完成各种计算任务 例7.8 求T = 8! = 1×2×3×…×8 例7.8 例7.8 T = 8! = 1×2×3×… 8。 t = 1 累乘器初值为1 For c = 1 To 8 t = t * c 累乘器,在原有积的基础上每次乘一个数 Next Print T=; t 程序执行结果是:T=40320 分析 c = 1 t ← t * c 1 1 c = 3 t ← t * c 1 * 2 3 c = 2 t ← t * c 1 2 c = 8 t ← t * c 1 * 2 * … 7 8 …… 累乘器 t = t * k 旧值。前n项之积 新乘的数 采用Print直接在窗体上输出结果,程序代码如下: Private Sub Form_Load() Show Dim pi As Single, c As Integer, s As Integer pi = 0 s = 1 s表示加或减运算 For c = 1 To 10000 Step 2 pi = pi + s / c s = -s 交替改变加、减号 Next c Print π=; pi * 4 End Sub 程序运行结果是: π=3.141397 例7.9 用π/4=1 - 1/3 + 1/5 - 1/7 + ……级数求π的近似值 (取前5000项来进行计算) 例7.9 For t = 1 To 3 If t = 1 Then a = 3 If t = 2 Then a = 2 If t = 3 Then a = 1 Print a; Next t Print t A. 3 3 3 3 B. 1 2 3 4 C. 3 2 1 4 D. 1 1 1 4 下列程序的运行结果是? 想一想 思考题 D For t = 1 To 3 If t = 1 Then a = 3 If t = 2 Then a = 2 If t = 3 Then a = 1 Print a; Next t Print t A. 3 3 3 4 B. 1 2
显示全部