As this.name is not working to access fields with the same name like a method parameter in static classes, I'm looking for a way to do so.
As an example i would like to do this:
static class test
{
private static string aString;
public static void method(string aString)
{
// aString (field) = aString (parameter)
}
}
use:
test.Astring = x;
i.e. replace this with the class name, test in this case.
static class test
{
private static string Astring="static";
public static void method(string Astring)
{
string passedString = Astring; // will be the passed value
string staticField = test.Astring; // will be static
}
}
if we call the method like test.method("Parameter"); the staticField will have the value static and passedString will have the value Parameter.
The keyword this denotes the current instance of the class; static
fields cannot be accessed through instance you should use the class
name instead for accessing the static field.
Note :- But please take care while naming the variables. Avoid giving same name in same class. It will be best if you define the class like the following
static class test
{
private static string StaticAstring="static";
public static void method(string passedAstring)
{
string staticField = StaticAstring; // will be static
string passedString = passedAstring; // will be the passed value
}
}
Related
I need to get string from one class to another class,
It is possible to set public string from method I mean like in this code:
class test
{
static void Main(string[] args)
{
load();
}
public class Data
{
public string datacollected { get; set; }
}
public static void load()
{
string fileName = "samplefile.json";
string jsonString = File.ReadAllText(fileName);
Data datacfg = new Data();
var datanew = System.Text.Json.JsonSerializer.Deserialize<List<Data>>(jsonString);
datacfg = datanew.First();
}
public string datacollected = datacfg.datacollected;
}
i want to use string datacollected in another class and in another public void
The datacollected member that is directly in the test class is not a property. It's a field. Fields that have an assignment on the same statement as the declaration are evaluated before* the class's constructor (ie: before the Main method runs).
You probably want it to be a property instead, which is evaluated each time you access the member. The simplest method to fix that is by adding a > after the equals.
public string datacollected => datacfg.datacollected;
You've got two other problems though.
datacollected (in the test class) isn't static. All of your methods are static, and therefor wouldn't be able to access the non-static member.
You've still got the problem where the datacfg is a local variable that is defined inside the load method. You can't use variables outside their defined scope.
Option 1: you only need the parsed file data in the method that called load.
Change load to return the parsed data, rather than save it to a class-global variable.
using System.Text.Json;
static class test
{
static void Main(string[] args)
{
Data loadedData = load();
}
public static Data load()
{
string fileName = "samplefile.json";
string jsonString = File.ReadAllText(fileName);
return JsonSerializer.Deserialize<List<Data>>(jsonString).First();
}
}
public class Data
{
public string datacollected { get; set; }
}
Option 2: If you really need some global variable, put the whole Data object up to a field instead. This doesn't use a property - there's really no advantage in this case.
using System.Text.Json;
static class test
{
// assuming you're using nullable reference types (the "?")
private static Data? loadedData;
static void Main(string[] args)
{
load();
Console.WriteLine(loadedData!.datacollected);
// "!" to tell compiler that you know loadedData
// shouldn't be null when executed
}
public static void load()
{
string fileName = "samplefile.json";
string jsonString = File.ReadAllText(fileName);
loadedData = JsonSerializer.Deserialize<List<Data>>(jsonString).First();
}
}
public class Data
{
public string datacollected { get; set; }
}
I'd go with Option 1 if at all possible.
* I don't remember if it's before, during, or after.
You can declare a class like this
public class UseData
{
private List<Data> _data=null;
public string datacollected
{
get
{
if (_data == null)
LoadData();
return _data.First().datacollected;
}
}
private void LoadData()
{
string fileName = "samplefile.json";
string jsonString = File.ReadAllText(fileName);
_data = System.Text.Json.JsonSerializer.Deserialize<List<Data>>(jsonString);
}
}
which have a private list of data and it loads from your json file at first time you called. Next time you call it, as the private _data object is filled, it wont load again and the datacollected property returns the first data object's datacollected string property.
public class Program
{
public static void Main(string[] args)
{
var c = check.myValue("Example 1"); //This is the pattern I've to use, don't want to create an object (Is it possible to use it with static class)
Console.WriteLine(c.result1);
Console.WriteLine(c.result2);
}
}
public static class check
{
public static void myValue(string qr)
{
public string result1 = "My Name" + qr;
public string result1 = "You're" + qr;
}
}
See here Online Example (Code is not working)
Every thing on main function I've to use exactly the same pattern because I'll use it in a lot of different classes and I don't want to create object each and every time by using non-static class.
Please correct me if I'm wrong
There's a lot wrong with the syntax of that code, which #Sergey addresses in his answer.
You appear to want to return an instance of a class from a static method, and that class should contain two properties.
You can do that by creating the actual, nonstatic class containing the properties:
public class Check
{
public string Result1 { get; set; }
public string Result2 { get; set; }
}
Then return a new instance from the static method therein:
public static Check MyValue(string qr)
{
var result = new Check();
result.Result1 = "My Name" + qr;
result.Result2 = "You're" + qr;
return result;
}
However, you're saying in the comments in your code that you don't want to use an object.
In that case it appears you want to use static properties. That's generally not recommendable, but it would look like this:
public static class Check
{
public static string Result1 { get; set; }
public static string Result2 { get; set; }
public static void MyValue(string qr)
{
Result1 = "My Name" + qr;
Result2 = "You're" + qr;
}
}
Then you can read Check.Result1 after calling the method MyValue().
Your code is totally wrong
myValue method returns void. You cannot assign void return value to variable.
You cannot have public modifiers for local variables.
You cannot have local variables with same name in same scope
If you want to return two values from method, then you should return object with two fields - custom class or tuple. You can also use out parameters, but I don't think it's your case
public static class Check
{
public static Tuple<string, string> MyValue(string qr)
{
return Tuple.Create($"My Name {qr}", $"You're {qr}");
}
}
With C# 7 it's a little bit better. You can write this method in one line and provide names for tuple properties
(string MyName, string YourName) MyValue(string qr) => ($"My Name {qr}", $"You're {qr}");
Usage
var result = Check.MyValue("Example 1");
Console.WriteLine(result.Item1); // result.MyName
Console.WriteLine(result.Item2); // result.YourName
You can practice with creating custom class with nicely named properties instead of using tuples.
Is there a way know which class has called a function in another class.
Eg:
public class A
{
public static string Aa = "test";
public void test()
{
B.testB();
}
}
public class B
{
public static void testB()
{
string Bb = A.Aa;
}
}
In the above example, i know the class A function has called the function in class B. But if there are many classes which will call the function in class B and all of those classes will have variable Aa in common, so how can i read its value and assign it to Bb. So in simple
string Bb = CalledClassName.Aa;
You could use the CallerMemberNameAttribute that was added with .NET 4.5. This will only get you the member name though:
public void SomeMethod ()
{
OtherMethod();
}
public void OtherMethod ([CallerMemberName] string memberName = null)
{
Console.WriteLine(memberName);
}
The attribute will fill the optional parameter at compile time, so it will actually call OtherMethod("SomeMethod").
You could also use a combination of accessing the stack trace and using reflection to read the Aa property of the type of the calling method. Note that this accesses debugging information, and is very vulnerable to changes in your code. It also has a bad performance, so you should avoid it. But just to show you how to use it:
public static void testB()
{
StackTrace stackTrace = new StackTrace();
Type callingType = stackTrace.GetFrame(1).GetMethod().DeclaringType;
FieldInfo field = callingType.GetField("Aa", BindingFlags.Public | BindingFlags.Static);
string Bb = (string) field.GetValue(null);
Console.WriteLine(Bb);
}
Use an interface, pass that in:
public interface AaInterface {
public string GetAa();
}
public class A : AaInterface
{
public static string Aa = "test";
public GetAa() { return Aa; }
public void test()
{
B.testB(this);
}
}
public class B
{
public static void testB(AaInterface pAa)
{
string Bb = pAa.GetAa();
}
}
I guess you are looking for something different than you are asking.
You should pass the instance of A to your method. All calling methods should pass the instance based on an interface. In that interface you put the properties and methods you want to share. In that way you can call the 'same' method for every passed instance.
public interface ISomeInterface
{
string Aa {get;}
}
public class A : ISomeInterface
{
public string Aa {get { return "a"; } }
}
Then you can pass it to this method:
public static void testB(ISomeInterface something)
{
string Bb = something.Aa;
}
Note that in this case, Aa is not allowed to be static. You could wrap that static in an instance property though.
If i understood your question correctly then you can pass a reference to a class instance in method as parameter then use 'is' operator to check its type:
public class A
{
public static string Aa = "test";
public void test(object calledClass)
{
if(calledClass is B) Aa = calledClass.Bb;
}
}
When you call this static method from class B just put :
A.Test(this)
P.S.
This is just an example of logic that you can use to achieve what you want
I geuss you can do something like this:
public class A {
public void test() {
B.testB(this);
}
}
public class B {
public static void testB(object sender) {
String className = sender.GetType().Name;
}
}
//To call
A a = new A();
a.test();
i have one main class and with in this main class i have another class A. class A has few static property and when i tried to access those static property from outside but getting error....not being possible
here is my classes structure
public class EShip
{
class Credentials
{
private static string _accessKey = "aaa";
private static string _accessPwd = "xxx";
private static string _accountNumber = "2222";
public static string AccessKey
{
get { return _accessKey; }
}
public static string AccessPassword
{
get { return _accessPwd; }
}
public static string AccountNumber
{
get { return _accountNumber; }
}
}
public static Credentials Credential
{
{ get; }
}
}
i try to expose that inner class by a main class property and from outside i try to do like
EShip.Credentials.AccessKey
EShip.Credentials.AccessPassword
it is not getting possible......suggest me good approach and why i am stuck. thnx.
Class Credentials is not public, therefore it's not accessible. Change that and you're able to do:
String key = EShip.Credentials.AccessKey;
Access Modifiers (C# Programming Guide)
public void main()
{
string test = "testing";
ChangeVal(test);
Console.WriteLine(test);
}
private void ChangeVal(string test)
{
test = "in child";
}
If String is a class.
and i pass string as a parameter to a function. change the value of that string in function.
But in main function it shows the previous values. It will print testing value.
when i created Foo class which has 2 member variable integer and string.
when i passed the object of the class as parameter and change value of the member variable in function.
It will give updated value in the main function
public class Foo
{
public string test = "testing";
public int i = 5;
}
public void main()
{
Foo obj=new Foo();
Console.WriteLine(obj.test);
ChangeVal(obj);
Console.WriteLine(obj.test);
}
private void ChangeVal(Foo obj)
{
obj.test = "in child";
obj.i = 5;
}
If string is the class. It will update the value of the variable.
May string is the sequence of Unicode character that's why it doesn't update the value in 1st case.
Can any body will explain this in detail.
change the value of that string in function
Strings are immutable. You can't change the value of a string. You can assign another string to the same reference, but you would need to pass the reference in by using ref.
public void main()
{
string test = "testing";
ChangeVal(ref test);
Console.WriteLine(test);
}
private void ChangeVal(ref string test)
{
test = "in child";
}
You Foo class, however, is mutable, so you can assign different values to its members.
Try to pass the parameter by reference to get the var updated in main thread:
private void SeString(ref string chain)
{
chain="new string";
}
Then call:
string variable="hello";
SeString(ref variable);
string output is "new string"