229: Using TryParse() in Place of an Invalid Cast Exception in C#

Making PDF417 in C# 229: Using TryParse() in Place of an Invalid Cast Exception
Listing 229: Using TryParse() in Place of an Invalid Cast Exception
Generating PDF 417 In Visual C#.NET
Using Barcode drawer for .NET Control to generate, create PDF 417 image in .NET framework applications.
double number; string input; SystemConsoleWrite("Enter a number: "); input = SystemConsoleReadLine(); if (doubleTryParse(input, out number)) { // Converted correctly, now use number // } else { SystemConsoleWriteLine( "The text entered was not a valid number"); }
Draw Barcode In C#
Using Barcode printer for .NET Control to generate, create bar code image in VS .NET applications.
Output 219 shows the results of Listing 229
Create PDF-417 2d Barcode In .NET
Using Barcode generation for ASP.NET Control to generate, create PDF417 image in ASP.NET applications.
OUTPUT 219:
Paint PDF 417 In .NET
Using Barcode printer for VS .NET Control to generate, create PDF417 image in .NET applications.
Enter a number: forty-two The text entered was not a valid number
PDF417 Creator In VB.NET
Using Barcode generation for VS .NET Control to generate, create PDF-417 2d barcode image in .NET framework applications.
The resultant value the code parses from the input string is returned via an out parameter in this case, number The key difference between Parse() and TryParse() is that TryParse() won t throw an exception if it fails Frequently, the conversion from a string to a numeric type depends on a user entering the text It is
Bar Code Creator In Visual C#
Using Barcode creation for .NET framework Control to generate, create barcode image in .NET framework applications.
Arrays
Create Bar Code In Visual C#
Using Barcode generator for VS .NET Control to generate, create bar code image in .NET applications.
expected, in such scenarios, that the user will enter invalid data that will not parse successfully By using TryParse() rather than Parse(), you can avoid throwing exceptions in expected situations (The expected situation in this case is that the user will enter invalid data)
Code 3 Of 9 Creator In Visual C#.NET
Using Barcode printer for .NET Control to generate, create Code39 image in Visual Studio .NET applications.
Arrays
Code 128 Code Set A Printer In C#
Using Barcode printer for VS .NET Control to generate, create Code 128 Code Set C image in Visual Studio .NET applications.
One particular aspect of variable declaration that 1 didn t cover is array declaration With array declaration, you can store multiple items of the same type using a single variable and still access them individually using the index when required In C#, the array index starts at zero Therefore, arrays in C# are zero-based
Generate ECC200 In Visual C#.NET
Using Barcode maker for VS .NET Control to generate, create Data Matrix 2d barcode image in VS .NET applications.
BEGINNER TOPIC Arrays Arrays provide a means of declaring a collection of data items that are of the same type using a single variable Each item within the array is uniquely designated using an integer value called the index The first item in a C# array is accessed using index 0 Programmers should be careful to specify an index value that is less than the array size Since C# arrays are zero-based, the index for the last element in an array is one less than the total number of items in the array Declaring an Array In C#, you declare arrays using square brackets First, you specify the type of the items within the array, followed by open and closed square brackets; then you enter the name of the variable Listing 230 declares a variable called languages to be an array of strings
Data Matrix Scanner In VS .NET
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in Visual Studio .NET applications.
Listing 230: Declaring an Array
UPC - 13 Creation In Java
Using Barcode printer for Java Control to generate, create EAN-13 image in Java applications.
string[] languages;
Draw EAN-13 In .NET
Using Barcode creator for ASP.NET Control to generate, create EAN-13 Supplement 5 image in ASP.NET applications.
Obviously, the first part of the array identifies the data type of the elements within the array The square brackets that are part of the declaration
EAN128 Generator In Java
Using Barcode printer for Java Control to generate, create EAN128 image in Java applications.
2: Data Types
Code 128A Printer In VS .NET
Using Barcode maker for VS .NET Control to generate, create Code 128 Code Set B image in Visual Studio .NET applications.
identify the rank, or the number of dimensions, for the array; in this case, it is an array of rank one These two pieces form the data type for the variable languages
Generate Bar Code In .NET Framework
Using Barcode maker for .NET Control to generate, create bar code image in VS .NET applications.
Language Contrast: C++ and Java Array Declaration
Generate Bar Code In .NET Framework
Using Barcode printer for ASP.NET Control to generate, create bar code image in ASP.NET applications.
The square brackets for an array in C# appear immediately following the data type instead of after the variable declaration This keeps all the type information together instead of splitting it up both before and after the identifier, as occurs in C++ and Java
Bar Code Printer In VS .NET
Using Barcode printer for Visual Studio .NET Control to generate, create barcode image in .NET applications.
Listing 230 defines an array with a rank of one Commas within the square brackets define additional dimensions Listing 231, for example, defines a two-dimensional array of cells for a game of chess or tic-tac-toe
Making Code39 In VB.NET
Using Barcode encoder for VS .NET Control to generate, create Code-39 image in Visual Studio .NET applications.
Listing 231: Declaring a Two-Dimensional Array
UCC - 12 Recognizer In Visual Studio .NET
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
// | | // ---+---+--// | | // ---+---+--// | | int[,] cells;
In Listing 231, the array has a rank of two The first dimension could correspond to cells going across and the second dimension represents cells going down Additional dimensions are added, with additional commas, and the total rank is one more than the number of commas Note that the number of items that occurs for a particular dimension is not part of the variable declaration This is specified when creating (instantiating) the array and allocating space for each element
Instantiating and Assigning Arrays Once an array is declared, you can immediately fill its values using a comma-delimited list of items enclosed within a pair of curly braces Listing 232 declares an array of strings and then assigns the names of nine languages within curly braces