Compling C# Expression with values

Question

I have combined two expression with Expression.And. How can I compile this new expression with actual values?

var expr1 = Expression.Equal(Expression.Parameter(typeof(int), "param1"), Expression.Parameter(typeof(int), "param2"));
var expr2 = Expression.Equal(Expression.Parameter(typeof(int), "param3"), Expression.Parameter(typeof(int), "param4"));
var finalExpression = Expression.And(expr1, expr2);

I'm trying to get to work somoething like this after substiting the parameters with values

bool returnBool =  Expression.Lambda<Func<bool>>(finalExpression).Compile()();

Answer 1

You need to compile it to a lambda with the same parameters:

var lambda = Expression.Lambda<Func<int, int, int, int, bool>>(
    finalExpression, param1, ...).Compile();
lambda(1, 2, 3, 4);

Note that you need to pass the same Expression.Parameter() instances used in the expression to Lambda().