4 language exchange source code K line normal + second contract + pledge

The exchange source code of this language integrates K-line normal display, second-level contract trading and pledge functions. Although its user interface design is a little rough and not beautiful enough, fortunately, its core functions are running normally, and the K-line chart display has no problems. This set of source code is relatively concise and clear in terms of functional implementation, and is very suitable for secondary development or as material for learning and research.