Loading native dll's at runtime-CodePudding

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#?

CodePudding user response：

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