tailieunhanh - Bonus Reference VB.NET Functions and Statements

This bonus reference describes the functions and statements that are supported by Visual Basic .NET, grouped by category. When you’re searching for the statement to open a file, you probably want to locate all file I/O commands in one place. This is exactly how this reference is organized. Moreover, by grouping all related functions and statements in one place, I can present examples that combine more than one function or statement. | Bonus Reference Functions and Statements This bonus reference describes the functions and statements that are supported by Visual Basic .NET, grouped by category. When you’re searching for the statement to open a file, you probably want to locate all file I/O commands in one place. This is exactly how this reference is organized. Moreover, by grouping all related functions and statements in one place, I can present examples that combine more than one function or statement. The majority of the functions are the same as in VB6. One difference is that many of the VB6 statements are implemented as functions in . Moreover, many VB6 functions have an equivalent method in a Framework class. VB programmers are so accustomed to the old func- tions that they will not consider the alternatives—at least for a while. The Len() function of VB6 returns the length of a string. In you can retrieve the length of a string with the Length method of a string variable. If strVar is declared as string variable, you can retrieve its length by calling the Length method: Dim strVar As String = “a short string” (“The string contains “ & & “ characters”) Or you can call the Len() function passing the name of the string as argument: Dim strVar As String = “a short string” (“The string contains “ & Len(strVar) & “ characters”) Most of the built-in functions are VB6 functions, and they accept optional arguments. uses overloaded forms of the same function, and this is an important difference you have to keep in mind as you work with the built-in functions. If you omit an optional argument, you must still insert the comma to indicate that an argument is missing. Optional arguments are enclosed in square brackets. The Mid() function, for example, extracts a number of characters from a string, and its syntax is newString = Mid(string[, start][, length]) The starting location of the characters to be extracted is specified by .