Accessing a function directly

[eluser]CodeIgniterNoob[/eluser]
I have a function that passes an id to a destination page that pulls data from a table based on that id. Everything works fine when the URL contains a number at the end like post/1, but when I hit the function directly like post/ it gives errors saying "Message: Missing argument 1 for welcome::post()" .

Is there a way to make that URL redirect to another page?