vb.net 2008 barcode generator FUNDAMENTAL TYPES: STRINGS, ARRAYS, AND ENUMS in C#.NET

Generate PDF417 in C#.NET FUNDAMENTAL TYPES: STRINGS, ARRAYS, AND ENUMS

else if ( str1->CompareTo( str2 ) == 0) { Console::WriteLine("The strings are both equal, with value {0}.", str1); } } Here is the output of Listing 5-5:

Implementing the IComparable interface allows strings to be used in all sorts of container classes where comparison is a requirement. For example, in 11, you ll see how to define a generic collection class that has a constraint indicating that any class used in the generic collection must implement IComparable. This allows the author of the generic class to assume certain functionality, such as the existence of the CompareTo method. The CompareTo method alone isn t rich enough to support all the factors that might be relevant in comparing strings in real-world code. Sometimes comparison must be case sensitive, other times comparison must be case insensitive. Additionally, comparison in some applications must be sensitive to culture, since alphabets and alphabetical order are dependent on locale. The CompareTo method also includes overloads that support comparison of substrings. There s also a CompareOrdinal method that is useful if the strings represent numbers and you want a comparison of the number.

The Format methods format a string for output. The .NET Framework formatting support is very rich, supporting a highly customizable output format and providing an extensible framework for defining your own custom formats as well. The same formatting rules are used for the Console class s WriteLine method for output to the console. The string used to specify the desired formatting and that acts as a template for the output is called the format string. The format string contains placeholders that are numbered starting with zero and surrounded by curly braces, as in the following string: Console::WriteLine("The population of {0} is {1}.", "Pleasantville", 500); This code substitutes Pleasantville for the {0} and 500 for the {1}. The type of the argument need not be supplied, as the language contains enough type information without any further specification. The number in curly braces is referred to as the index. It is followed, optionally, by a comma and number specifying the minimum width of the field. The sign of the number specifies the justification (positive for right-justification, negative for left-justification). One can also append a colon and a formatting string that is used to customize the output format. The available formatting strings are dependent on the type. A variety of formatting codes exists for formatting numeric output, as well as date, time, and currency output, which is dependent on the locale. The following sections provide detailed examples.

The Width Field (or Alignment Specifier)

Listing 5-6 provides some examples of formatting using the width field, including a negative width indicating left justification, and a currency formatting string the c2 following the colon in the Price column, which is ignored when used with a string. Listing 5-6. Formatting Strings Using the Width Field // string_alignment_specifier.cpp using namespace System; int main() { // The format string is interpreted as follows: // { 0, -30 } 30 characters in width, left-justified. // { 1, 10 } 10 characters in width, right-justified. // { 2, 10:c2 } 10 characters in width, currency with 2 decimal places. String^ format = "{0,-30}{1,10}{2,10:c2}"; String^ header = String::Format(format, "Item", "Quantity", "Price"); String^ str1 = str1->Format(format, "Matches, Strike Anywhere", 10, 0.99); String^ str2 = str2->Format(format, "Gloves", 1, 12.50); String^ str3 = str3->Format(format, "Iodine", 1, 4.99); Console::WriteLine(header); Console::WriteLine(str1 + "\n" + str2 + "\n" + str3); } The output of Listing 5-6 on U.S. English systems is as follows: Item Matches, Strike Anywhere Gloves Iodine Quantity 10 1 1 Price $0.99 $12.50 $4.99

Formatting in C runtime functions such as printf involves the use of formatting characters for various data types and, in particular, certain formatting characters for decimal or hexadecimal output, exponential format, and so on. The usual numeric formatting characters from C are supported, as well as additional formats for currency, and a special round-trip format specifically to ensure accurate results when reading the data back in using the Read or ReadLine methods. The code in Listing 5-7 shows the typical use of these formats. The formatting specifier follows the colon after the index (and optional alignment specifier specifying the width of the field) in the format string. In the following example, the alignment specifier is not used, and the index is always zero since we only have one variable to format.