' atoi3.vb Imports System Class ATOI3 Public Shared Sub Main() Dim str As String = "123456789" Dim num As Integer = Convert.ToInt32(str) Console.WriteLine(num) ' 出力:123456789 str = Convert.ToString(num) Console.WriteLine(num) ' 出力:123456789 'str = "1,234,567,890" 'num = Convert.ToInt32(str) ' '例外:System.FormatExceptionが発生 End Sub End Class ' コンパイル方法:vbc atoi3.vb