Modular programming is implinted by using subroutines, a group of instructions that performs a limited processing task, such as printing a portion of reporet, reading an input record, or calculating a square root.

An early stage in the development of structured programming. A program is broken down into pieces, or modules which can be coded and tested separately. That is called modular programming.

External suboroutines are used to tasks that more than one program is likely to want perfomed. To use an external subroutine, the programmer needs to know where to find it, whats its name is, how to send data to it, and how the answer will come back.Once this technicalities are deal with, however, the programmer can make use of the code to perform a task, with confidence that the subroutine will provide the correct result.

An internal subroutine is part of the program that uses it.

The subrutines flowchat begins and ends by Terminal outline