What is TOP-DOWN & BOTTOM-UP approach?

Answer 1

it can be described in different ways according to in which contrast you are talking.
in programming languages top-down term is used when the work is or to be done in step wise procedure.
and in bottom up approach term used when work is or to be done in simultaneously.

Answer 2

//topdown,-,bottomup explained in terms of c and c++ programming languages
in c it uses top down approach
and in c++ it uses bottom up approach
as the word approach says it means the way a programmer wants to build a program
in c we first declare all the variables, functions and then use them but in c++
first of all after including header files etc we start to write the class means here we are not using or writing main function but we are writing the class and if definition at the start of the program
as we all know in c/c++ the program execution begins from main() function here then we declare the objects for the class obviously here we all know that if the class is written at first then the main will be at the bottom of the program and the program begins from the bottom and will go to the classes and its methods etc ..............
that is the basic difference between a top down approach and a bottom up approach

Answer 3

it's a good question and often asked in interviews, coz ur answer shows ur knowledge of programming paradigms.

is it true that procedural programming always comes under bottom down approach and

Object oriented under bottom up approach?

Answer 4

its a method of solving problems........
from top to bottom it break's problem into sub problem.......

Answer 5

ok, that's y I m getting rejected 😄

Answer 6

thank you for the breakdown Martin

Answer 7

Top down is whereby a solution is sort where the problem is broken down into smaller concepts until each problem can be solved in a few steps

Bottom up is where a solution is sort at the lowest level or subsystems and progresses upwards to the design of the main module or main system

Answer 8

top-down=plan->goal
bottom-up=goal->plan

Answer 9

@Taylor thank you :)

Answer 10

Generally in a C programs the execution starts from the top. It goes on .
But in case of C++ generally we use to give the main class or main function at the bottom . Since we know that execution starts from the main function or method then it became as bottom up approach

Answer 11

ANSWER because the procedure oriented programming languages give the importance to the functions and step sequence that's why this language is called the top down approach and if we talk about the object oriented programming languages this languages are give main importance to the data or security this is the main reason OOP is called bottom up approach.

Answer 12

@Bharath Verma, I ll be surprised if its so simple , anyways suppose I need to make a customer feedback app where his previous feedbacks is used everytime to provide him with the most suitable product to buy in the dashboard.

USe any stack , language u prefer, since it's about designing can u tell how should I proceed in if

# it's TOP- DOWN approach I took
# it's BOTTOM - UP approach I took

some supportive arguments will be helpful too, to show why that decision is considered TOP- DOWN/bottom - up

Answer 13

//topdown,-,bottomup explained in terms of c and c++ programming languages
in c it uses top down approach
and in c++ it uses bottom up approach
as the word approach says it means the way a programmer wants to build a program
in c we first declare all the variables, functions and then use them but in c++
first of all after including header files etc we start to write the class means here we are not using or writing main function but we are writing the class and if definition at the start of the program
as we all know in c/c++ the program execution begins from main() function here then we declare the objects for the class obviously here we all know that if the class is written at first then the main will be at the bottom of the program and the program begins from the bottom and will go to the classes and its methods etc ..............
that is the basic difference between a top down approach and a bottom up approach

Answer 14

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 module (or small program) to give rise to more complex program, thus making the original modules of the emergent program.

Answer 15

little confusion

Answer 16

Topdown and bottom up is a parsing approach. How compiler can detect and solve the code. Topdown means start from roof or top and end with bottom or variable and calculate it.
bottom up is start from variable or bottom and move towards top or roof. finally calculate it.
It is the flow of data from one expression to others.

Answer 17

the function has to be declared or defined before it is called

Answer 18

it's my knowledge bro

Answer 19

nope @morpheus

Answer 20

in top down we write main() function first and then write user-defined functions.....

in bottom up approach we write user-defined functions first and then write the main() function