Skip to main content

Default value and TryParse

Ce vi se pare ciudat in urmatorul cod?
int value;
if(!int.TryParse(text.ToString(), out value))
{
value = 0;
}
In mod default, toate tipurile de numere de tip value type au valoarea default 0. Din aceasta cauza nu mai este nevoie sa setam value 0. Ajunge sa avem doar urmatorul cod:
int value;
int.TryParse(text.ToString(), out value);
In cazul in care vrem sa obtinem valoarea default pentru orice tip de data putem sa ne folosim de "default". Acest keyword returneaza null pentru toate tipurile referinta si 0 (zero) pentru value type. In cazul structuriilor acesta o sa returneze structura noastra, iar fiecare element din structura o sa fie inializat cu default value pentru acesta.
var value1 = default(int);        // 0
var value2 = default(double); // 0
public struct Point
{
public int x, y;
public Point(int x, int y)
{
this.x = x;
this.y = y;
}
}
var value3 = default(Point); // X si Y o sa fie 0
var value 4 = default(MyCustomClass) // null

In cazul in care vrem ca codul nostru sa fie mai usor de inteles putem ca in momentul in care il declaram pe value sa il setam cu default(int) sau cu 0. Eu prefer a doua varianta deoarece este mult mai usor de citit.

Comments

  1. Problema cu bucata nr.2 de cod (`int value;
    int.TryParse(text.ToString(), out value);`) este ca daca iti vine zero nu stii daca zero era efectiv in string-ul respectiv sau a esuat parse-area...

    ReplyDelete
    Replies
    1. Drept. In primul exemplu, se seta valoarea default la 0 daca parsa a esuat (nu mai era nevoie sa executam sau sa logam ceva daca aceasta a eusat). In al doilea exemplu se obtine acelasi comportament, valoarea default fiind setata pe 0.

      Delete

Post a Comment

Popular posts from this blog

Windows Docker Containers can make WIN32 API calls, use COM and ASP.NET WebForms

After the last post , I received two interesting questions related to Docker and Windows. People were interested if we do Win32 API calls from a Docker container and if there is support for COM. WIN32 Support To test calls to WIN32 API, let’s try to populate SYSTEM_INFO class. [StructLayout(LayoutKind.Sequential)] public struct SYSTEM_INFO { public uint dwOemId; public uint dwPageSize; public uint lpMinimumApplicationAddress; public uint lpMaximumApplicationAddress; public uint dwActiveProcessorMask; public uint dwNumberOfProcessors; public uint dwProcessorType; public uint dwAllocationGranularity; public uint dwProcessorLevel; public uint dwProcessorRevision; } ... [DllImport("kernel32")] static extern void GetSystemInfo(ref SYSTEM_INFO pSI); ... SYSTEM_INFO pSI = new SYSTEM_INFO(

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine: threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration: TeamCity .NET 4.51 EF 6.0.2 VS2013 It see

Navigating Cloud Strategy after Azure Central US Region Outage

 Looking back, July 19, 2024, was challenging for customers using Microsoft Azure or Windows machines. Two major outages affected customers using CrowdStrike Falcon or Microsoft Azure computation resources in the Central US. These two outages affected many people and put many businesses on pause for a few hours or even days. The overlap of these two issues was a nightmare for travellers. In addition to blue screens in the airport terminals, they could not get additional information from the airport website, airline personnel, or the support line because they were affected by the outage in the Central US region or the CrowdStrike outage.   But what happened in reality? A faulty CrowdStrike update affected Windows computers globally, from airports and healthcare to small businesses, affecting over 8.5m computers. Even if the Falson Sensor software defect was identified and a fix deployed shortly after, the recovery took longer. In parallel with CrowdStrike, Microsoft provided a too