多重循环与常用算法.ppt

1多重循环与常用算法一、多重循环的执行步骤二、打印九九乘法表三、打印字符等腰三角形四、两个经典算法(1)求最大公约数与最小公倍数(2)判断素数在一个循环体内又包含了一个完整的循环结构称为循环的嵌套。循环嵌套对 For 循环语句和 Do … Loop 语句均适用。例1:星号三角形 Private Sub Form_Click() Dim i, x For i = 1 To 9 Print Tab(20 - i) ; For j = 1 To 2 * i - 1 Print " *"; Next j Print Next i End Sub 4 例2打印九九乘法表思考: 打印上三角或下三角程序如何改动? Private Sub Form_Click () Dim se As String Print Tab(35); " 九九乘法表" Print Tab(35); "-----------" For i = 1 To 9 For j = 1 To 9 se = i & " × " & j & "=" & i * j Print Tab((j - 1) * 7); se; Next j Print Next i End Sub EX1 :打印如下排列: EEEEE C BB Private mand1_Click() For i = 1 To 4 For j = 1 To ___ Print _________ Next j Print Next i End Sub i+1 Chr(65 + i) ; 例3:三层 FOR 循环练习,产生并显示由数码 1、2、 3构成的所有三位数,并统计这些三位数的个数。 Private mand1_Click() Dim x As Integer, n As Integer Dim a As Integer, b As Integer, c As Integer n = 0 For a = 1 To 3 For b = 1 To 3 For c = 1 To 3 x = 100 * a + 10 * b + c n = n + 1 Print x; If n Mod 10 = 0 Then Print Next c Next b Next a Print Print " 三位数的个数是"; n End Sub