Can I programmatically add a string to the translation interface? I have used t() to translate a string value. To translate it from the user interface, I first need to view the page on which this string is displayed in a different language. Only then, the string is added to the translate interface.

I want to be able to translate the string before doing that. Can I programmatically add the string to the translation interface?
Assuming that your question is in regard to translating a (custom) module or theme. In that case, I'm using the Translation template extractor to get all strings of a module/theme that are used in the t() functions. For more information about using this module, look at this discussion. Though a pretty old discussion, it's still very useful.