Difference between top-down and bottom-up approaches

difference between a top-down approach and a bottom-up approach in programming.

Top-down Approach Bottom-up Approach
A top-down approach is essentially the breaking down of a program to gain insight into its compositional small program (or module) in a reverse engineering fashion. A bottom-up approach is the piecing together of modules (or small programs) to give rise to a more complex program, thus making the original modules of the emergent program.
Structure / procedure-oriented programming languages like C programming language follow a top-down approach. Object-oriented programming languages like C++ and JAVA programming language follow a bottom-up approach.
A top-down approach begins with high-level design and ends with low-level design or development. A bottom-up approach begins with low-level design or development and ends with high-level design.
In the top-down approach, the main function is written first and all sub-functions are called from the main function thus, sub-functions are written based on the requirement In the bottom-up approach, code is developed from modules and then these modules are integrated with the main function
In top-down, you start building the highest level of abstraction and then make small bits that will fit it. To put it in the simplest way, bottom-up means, you make the smallest pieces of your program first and then use them as blocks to build a bigger program.