61 lines
1.3 KiB
Text
61 lines
1.3 KiB
Text
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REM integer history variable
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Type HistoryInt
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As Integer Ptr values
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As Integer cnt
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As Integer capacity
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End Type
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Function InitHistory() As HistoryInt Ptr
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Dim As HistoryInt Ptr hist = Allocate(Sizeof(HistoryInt))
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hist->capacity = 10
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hist->values = Allocate(hist->capacity * Sizeof(Integer))
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hist->cnt = 0
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Return hist
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End Function
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Sub SetInt(hist As HistoryInt Ptr, value As Integer)
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If hist->cnt >= hist->capacity Then
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hist->capacity *= 2
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hist->values = Reallocate(hist->values, hist->capacity * Sizeof(Integer))
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End If
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If hist->cnt = 0 Then
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hist->values[hist->cnt] = 0
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hist->cnt += 1
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End If
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hist->values[hist->cnt] = value
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hist->cnt += 1
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End Sub
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Sub ShowHistory(hist As HistoryInt Ptr)
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For i As Integer = 0 To hist->cnt - 1
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Print hist->values[i]
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Next
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End Sub
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Function UndoInt(hist As HistoryInt Ptr) As Integer
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If hist->cnt <= 1 Then Return hist->values[0]
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hist->cnt -= 1
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Return hist->values[hist->cnt - 1]
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End Function
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' Main program
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Randomize Timer
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Dim As HistoryInt Ptr x = InitHistory()
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For i As Integer = 0 To 3
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SetInt(x, Int(Rnd * 50) + 100)
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Next
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Print "x history:"
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ShowHistory(x)
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Print
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For i As Integer = 0 To 3
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Print "undo, x ="; UndoInt(x)
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Next
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Sleep
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