C# foreach within a foreach loop

// Integrate forces for each body.
	foreach (RigidBodyBase body in doc.Bodies)
	{
		// Don't move background-anchored bodies.
		if (body.anchored) continue;

        // This is where we will add Each Body's gravitational force
        //  to the total force exerted on the object.

        // For each other body, get it's point and it's mass.

            // Find the gravitational force exterted between target body and looped body.
                // Find distance between bodies.
                    // vector addition
                // Force = G*mass1*mass2/distance^2
            // Find vector of that force.
            // Add Force to TotalGravityForce
        // loop until there are no more bodies.
        // Add TotalGravityForce to body.totalForce

	}

foreach( RigidBodyBase body in doc.Bodies)
     foreach ( RigidBodyBase otherBody in doc.Bodies)
         if (!otherBody.Anchored && otherBody != body)  // or otherBody.Id != body.Id -- whatever is required...
              // then do the work here

foreach (RigidBodyBase body in doc.Bodies)
       body.TotalForce += body.GravityForce;

int l = doc.Bodies.Count;
for ( int i = 0; i < l; i++ )
    for ( int j = i + 1; j < l; j++ )
        // Do stuff

foreach (RigidBodyBase body in doc.Bodies)
{
   Integrateforces(ref body, Bodies);
}

...

public void Integrateforces(RigidBodyBase out body, RigidBodyBase[] Bodies)
{
  //Put your integration logic here
}