1. The following code example will illustrate how we used to have to use TryParse to check if a string value is a valid integer. You will notice that we had to declare the integer variable intVal, which was used as the out variable. The intVal variable would just sort of hang there in mid air, usually not initialized and waiting to be used in  TryParse.

        string sValue = "500";

        int intVal;
        if (int.TryParse(sValue, out intVal))
        {
          WriteLine($"{intVal} is a valid integer");
          // Do something with intVal
        }

2. In C# 7.0 this has been simplified, as can be seen in the following code example. We can now declare the out variable at the point where it is passed as an out parameter, like so:

        if (int.TryParse(sValue, out int intVal))
        {
          WriteLine($"{intVal} is a valid integer");
          // Do something with intVal
        }

3. This is a small change, but a very nice one. Run the console application and check the output displayed.

4. As we are declaring the out variable as an argument to the out parameter, the compiler will be able to infer what the type should be. This means that we can also use the var keyword, like this:

        if (int.TryParse(sValue, out var intVal))
        {
          WriteLine($"{intVal} is a valid integer");
          // Do something with intVal
        }