TDD ( Test Driven Development):-
 1. It well supports unit tests and having programming
paradigm that is bit more flexible in regards to scope changes.

2. Having unit tests available will make our code more
maintainable over the long run is invaluable because we can
modify our code without fear such as when we are
adding/modifying functionality or refactoring.

3. It could be considered crucial when we have projects
where the scope is likely to change throughout the
development lifecycle like in the case where the functional
specifications are not clearly defined before we begin
producing code.


SDLC should be in the following way

1. As a first step, we'll define the interfaces out software
will adhere to.

2. Add a test
3. Run all tests and watch the new one fail (and the rest
succeed)
4. Modify our code to make the test succeed
5. Run all tests and watch them succeed
6. Refactor, if necessary
7. Run tests to ensure everything still works
8. Repeat

These are the steps we follow for TDD SDLC.


Agile SDLC:-
1. Agile aims to reduce risk by breaking projects into
small, time-limited modules or timeboxes ("iterations") with
each interation being approached like a small,
self-contained mini-project, each lasting only a few weeks.

2. Each iteration has it own self-contained stages of
analysis, design, production, testing and documentation.

3. In theory, a new software release could be done at the
end of each iteration, but in practice the progress made in
one iteration may not be worth a release and it will be
carried over and incorporated into the next iteration.

4. The project's priorities, direction and progress are
re-evaluated at the end of each iteration.

Hope this might give you all an idea.