In the use case diagram, we draw use cases as an ellipse. Are the use cases the same as functions? I mean by functions, those functions which we write in the program.Thank you in advance.
The word function has several meanings. One of them is similar to the meaning of use case. Another is mathematical function. Yet another is computer routine. Wiktionary lists a few more.
From my experience use case is what the code is used for and function is what the code does. For example you may have a subroutine that calculates the length of the minnimal path between two nodes in a graph but a specific use case may be to find the minimal length between two points in a maze (when represented as a graph).