29、Visual Basic编程技巧：数据加密与决策结构

Visual Basic编程技巧：数据加密与决策结构

文本文件的简单加密

在处理文本文件时，有时需要对其中的信息进行加密。一种简单的加密方法是通过对ASCII字符代码进行操作。以下是一段代码示例：

OpenFileDialog1.Filter = "Text files (*.txt)|*.txt"
If OpenFileDialog1.ShowDialog() = DialogResult.OK Then 'display Open dialog box
    If My.Computer.FileSystem.FileExists(OpenFileDialog1.FileName) Then
        Try 'open file and trap any errors using handler
            allText = My.Computer.FileSystem.ReadAllText(OpenFileDialog1.FileName)
            'now, decrypt string by subtracting one from ASCII code
            charsInFile = allText.Length 'get length of string
            For i = 0 To charsInFile - 1 'loop once for each char
                letter = allText.Substring(i, 1) 'get character
                decrypt = decry