modular programming

break down large problem into smaller problems. break down a large program into sub- procedures (modules)

do not return a value

do return a value

• each small prob is easier to solve • can share programming among a team • program more readable • modules are re- usable

a new area of memory opens while the module runs and closes when it finishes running

can only be used inside the module lost when the module closes

can be used anywhere in the program changes to them are permenant

values passed from main prog to module are used like variables in the module

when function stops a single value can be returned to the main program. it must be captured or it will be lost.

module gets a copy of the value, and it does not change the values in the main program

the module gets access to the original variable’s memory location. therefore it can change values used in the main program without using return.