1、算法说明
1) 顺序查找
逐个元素找,如果有,则记录位置,然后跳出循环;否则,查找失败。
代码如下:
以下是引用片段:
PRivate Sub Search(a(), ByVal Key, Index As Integer)
Dim i%
For i = LBound(a) To UBound(a)
If a(i) = Key Then '找到,将元素下标保存在index中并结束查找
Index = i
Exit Sub
End If
Next i
Index = -1 '若没找到,则index值为-1
End Sub
2) 二分法查找
顺序查找效率低下,当数组有序排列时,可以使用二分法查找提高效率。
算法思想:
>
代码如下:
以下是引用片段:
Private Sub birSearch(a(), ByVal low%, ByVal high%, ByVal Key, index%)
Dim mid As Integer
If low > high Then '没有查找到
index = -1
Exit Sub
End If
mid = (low + high) \ 2 '取查找区间的中点
If Key = a(mid) Then '查找到,返回下标
index = mid
Exit Sub
ElseIf Key < a(mid) Then '查找区间在上半部分
high = mid - 1
Else
low = mid + 1 '查找区间在下半部分
End If
Call birSearch(a, low, high, Key, index) '递归调用查找函数
End Sub
调用方法:
以下是引用片段:
Private Sub Command1_Click()
Dim a(11)
a(1) = 5: a(2) = 13: a(3) = 19: a(4) = 21: a(5) = 37
a(6) = 56: a(7) = 64: a(8) = 75: a(9) = 80: a(10) = 88: a(11) = 92
Dim ind As Integer
Call birSearch(a, LBound(a), UBound(a), 21, ind)
Print ind
End Sub
2、实战练习 补充代码(2002春二(9))
C盘根目录下stu.txt文件中以下的格式保存着学生姓名及班号信息。本程序的功能是:读取该文件中的数据,再利用InputvBox输入要查找的学生姓名,通过顺序查找,给出找到或找不到的信息。附图是某同学被找到时显示的信息窗口。
张文,机械01
李明,机械01
王文卉,机械01
…
何宇宙,电子02
以下是引用片段:
Option Explicit
Option Base 1
Private Sub Form_click()
Dim stu() As String, glass() As String, i As Integer
Dim n As Integer, name As String, k As Integer
Open "c:\stu\stu.txt" For Input As #11
Do While (1)
(2)
ReDim Preserve stu(n), glass(n)
Input #11, stu(n), glass(n)
Loop
name = InputBox("输入欲查找的学生姓名:")
Call search(name, stu, k)
If k <= n Then
MsgBox (3)
Else
MsgBox "无此人。"
End If
Close #11
End Sub
Private Sub search(name As String, stu() As String, k As Integer)
Dim i As Integer
For i = 1 To UBound(stu)
If name = stu(i) Then
(4)
End If
Next i
(5)
End Sub