Let’s say I have an extern method that is used to calculate the square root of a number. Like:
using System;
public static class Program
{
Public static extern double Sqrt(double x);
public static void Main(string[] args)
{
Console.WriteLine(Sqrt(64));
}
}
For the extern method to work, I will have to load a DLL which is usually done by using DllImport.
But let’s say I want to load the DLL at runtime by calling a method, like in Java:
System.load(“Path to DLL”);
Can this be done in C#?
You can import the same LoadLibrary that you're accustomed to using.
[DllImport("kernel32.dll")]
public static extern IntPtr LoadLibrary(string lib);
[DllImport("kernel32.dll")]
public static extern void FreeLibrary(IntPtr module);
[DllImport("kernel32.dll")]
public static extern IntPtr GetProcAddress(IntPtr module, string proc);
Example use (you should add error handling):
delegate int MyDelegate(int n, [MarshalAs(UnmanagedType.LPStr)] string s);
var module = LoadLibrary("Foo.dll");
var method = GetProcAddress(module, "doSomething");
var doSomething = (MyDelegate)Marshal.GetDelegateForFunctionPointer(method, typeof(MyDelegate));
var result = doSomething(2, "Hello world!");
FreeLibrary(module);
See this article