C# Cookbook

3.13. Converting Between Simple Types in a Language Agnostic Manner

Problem

You need to convert between any two of the following types: bool, char, sbyte, byte, short, ushort, int, uint, long, ulong, float, double, decimal, DateTime, and string. Different languages sometimes handle specific conversions differently; you need a way to perform these conversions in a consistent manner across all .NET languages. One situation where this recipe is needed is when VB.NET and C# components communicate within the same application.

Solution

Different languages sometimes handle casting of larger numeric types to smaller numeric types differently—these types of casts are called narrowing conversions. For example consider the following Visual Basic .NET (VB.NET) code which casts a Single to an Integer:

' Visual Basic .NET Code:
Dim initialValue As Single
Dim finalValue As Integer

initialValue = 13.499
finalValue = CInt(initialValue)
Console.WriteLine(finalValue.ToString( ))

initialValue = 13.5
finalValue = CInt(initialValue)
Console.WriteLine(finalValue.ToString( ))

initialValue = 13.501
finalValue = CInt(initialValue)
Console.WriteLine(finalValue.ToString( ))

This code outputs the following:

13
14
14

Notice that using the CInt cast in VB.NET uses the fractional portion of the number to round the resulting number.

Now let’s convert this code to C# using the explicit casting operator:

// C# Code: float initialValue = 0; int finalValue = 0; initialValue = (float)13.499; finalValue = (int)initialValue; ...