What is static?
Based on Microsoft (father of C-Sharp), it is modifier to declare a static member, which belongs to the type itself rather than to a specific object. For example, class have structure following:
class Test(){
public string Content;
}
In main function, we have:
static void Main(string[] args){
var t1 = new Test() { Content = "Test 1" };
var t2 = new Test() { Content = "Test 2" };
Console.WriteLine(t1.Content); //output: Test 1
Console.WriteLine(t2.Content); // output: Test 2
}
So we can see the output will difference with other instance. But if we use static in class, what happen?
class Test(){
public static string Content;
}
And update in main function:
static void Main(string[] args){
var t = new Test() { };
//error here because you can't access static property through by instance
Console.WriteLine(t.Content);
Test.Content = 'Static Content'
Console.WriteLine(Test.Content); //output: Static Content
ChangeContent("Update content with function");
Console.WriteLine(Test.Content); //output: Update content with function
}
static void ChangeContent(string content)
{
Test.Content = content;
}
Compare main before and after, we have table conclusion:
| Non static | Static | |
|---|---|---|
| Create at | New instance create | Compiler time |
| Access by | Instance | Class |
| Value | Follow the instance | Follow the class |
| Life time | Until the instance deallocate | Until program end |
P/s: With static keyword, the variable will be stored in heap memory, below is short description about stack & heap:
| Stack | Heap | |
|---|---|---|
| Store | - Primitive type - Reference variable - Function call |
- Object - Static type |
| Structure | Last In First Out (LIFO) | Dynamic |
| Performance access | Faster | Slower |
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