Sortable with time zone information in Visual C#.NET

Draw PDF417 in Visual C#.NET Sortable with time zone information

Day of month as digits with no leading zero for single-digit days Day of month as digits with leading zero for single-digit days Day of week as a three-letter abbreviation Day of week as its full name Month as digits with no leading zero for single-digit months Month as digits with leading zero Month as three-letter abbreviation Month as its full name Year as last two digits, with no leading zero Year as last two digits, with leading zero Year represented by four digits

Earlier examples have overridden the ToString() function to provide a string representation of a function. An object can supply different formats by defining the IFormattable interface and then changing the representation based upon the string of the function. For example, an Employee class could add information with a different format string. This example: using System; class Employee: IFormattable { public Employee(int id, string firstName, string lastName) { this.id = id; this.firstName = firstName; this.lastName = lastName; }

public string ToString (string format, IFormatProvider fp) { if ((format != null) && (format.Equals("F"))) return(String.Format("{0}: {1}, {2}", id, lastName, firstName)); else return(id.ToString(format, fp)); } int id; string firstName; string lastName; } class Test { public static void Main() { Employee fred = new Employee(123, "Fred", "Morthwaite"); Console.WriteLine("No format: {0}", fred); Console.WriteLine("Full format: {0:F}", fred); } } produces the following output: No format: 123 Full format: 123: Morthwaite, Fred The Format() function looks for the F format. If it finds it, it writes the full information. If it doesn t find it, it uses the default format for the object. The Main() function passes the format flag in the second WriteLine() call.

Numbers are parsed using the Parse() method provided by the numeric data types. You can pass flags from the NumberStyles class to specify which styles are allowed, and you can pass a NumberFormatInfo instance to control parsing. A numeric string produced by any of the standard format specifiers (excluding hexadecimal) is guaranteed to be correctly parsed if the NumberStyles.Any style is specified. This example:

using System; class Test { public static void Main() { int value = Int32.Parse("99953"); double dval = Double.Parse("1.3433E+35"); Console.WriteLine("{0}", value); Console.WriteLine("{0}", dval); } } produces the following output. 99953 1.3433E35

Using XML in C#

Although C# supports XML documentation (see 38), C# doesn t provide any specific language support for using XML. That s okay, however, because the CLR provides extensive support for XML. Some areas of interest are the System.Data.Xml and System.Xml namespaces.

The .NET CLR provides I/O functions in the System.IO namespace. This namespace contains classes for doing I/O and for other I/O-related functions, such as directory traversal, file watching, and so on. Reading and writing happens using the Stream class, which merely describes how bytes can be read and written to some sort of backing store. Stream is an abstract class, so in practice classes derived from Stream will be used. The classes listed in Table 34-5 are available. Table 34-5. Stream Types in the System.IO Namespace

A stream on a disk file A stream that s stored in memory A stream on a network connection Implements a buffer on top of another stream A stream that can compress or decompress data, passing through it using GZIP (RFC 1952) A stream that can compress or decompress data, passing through it using LZW77 (RFC 1951)

With the exception of BufferedStream, GZipStream, and DeflateStream, which sit on top of another stream, each stream defines where the written data will go. The Stream class provides raw functions to read and write at a byte level, both synchronously and asynchronously. Usually, however, it s nice to have a higher-level interface on top of a stream, and you can select from several supplied ones depending on what final format you want.