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Structured Programming in Software Engineering

The use of organised, modular code structures to increase the readability, effectiveness, and maintainability of software systems is emphasised by the structured programming paradigm. As a solution to the perceived issues with unstructured programming, which lacked a clear control flow and made programmes challenging to comprehend and maintain, it was created in the late 1960s.

  • In structured programming, we break down the entire programme into manageable parts to make it easier to grasp. Structured programming's goal is to linearize control flow within a computer programme such that it executes in the same order that the code was written. The program's static and dynamic structures are like each other. This improves the program's readability, testability, and modifiability. The list of permitted applications might be limited to single enter, single exit forms to regulate this linear flow of control.

Purpose of Structured Programming:

By offering a planned and organised approach to programming, structured programming aims to enhance the creation and upkeep of software systems.

The following are some of the main goals and purposes of structured programming:

  • Clarity: Improving code clarity is the main goal of structured programming. It is simpler to comprehend the logic and operation of the programme when a complicated challenge is divided into smaller, clearly defined modules.
  • Maintainability: The goal of structured programming is to make software systems easier to maintain. Modular code architectures allow for the modification of specific modules without impacting the programme.
  • Reusability: One goal of structured programming is to encourage the reuse of code. Code is organised into modular components that may be utilised in other applications or programmes.
  • Scalability: Structured programming offers a scalable method for creating software. An issue can be divided into smaller modules, making it easier to extend or modify the system as needs change.

Structure of structured programming:

It is possible to comprehend the structure of structured programming by looking at its essential elements and how they are related. An overview of the structure is provided here:

  1. Start: The start symbol, which denotes the program's entrance point, is where the flowchart starts.
  2. Main Program: The primary programme serves as the program's entry point. It offers the general framework and arrangement of the code. Typically, it contains of the program's primary logic, control structures, and function calls.
  3. Functions: Self-contained pieces of code known as functions or procedures carry out certain duties. They are made to be modular and reusable. Functions accept input parameters, carry out calculations, and, if necessary, provide results. They may be accessed through other functionalities or the main programme.
    • Control Structures: 
      Control structures are represented by symbols in the form of diamonds. They regulate the execution's flow based on certain circumstances.
    • Arrows that flow linearly from one assertion to the next reflect the order of the statements in a sentence.
    • Diamonds with branching routes are used to depict selection structures like if-else or switch expressions. The condition is assessed, and depending on the outcome, alternative courses in the programme flow are taken.
    • Iteration: Rectangles with arrows looping back to the beginning are used to illustrate iteration structures like for, while, and do-while loops. Till the required condition is satisfied, the loop will keep running.
  4. Structured data: Data that has been structured has been arranged into the proper data structures, such as arrays, records, or objects. These structures make it possible to manipulate and store data in an effective manner. They can be utilised inside functions or sent between them as arguments.
  5. End: The flowchart's last symbol, the word "end," denotes that the programme has finished running.

Key rules in Structured Programming:

  • Top-down design: This principle calls for employing a hierarchical method to divide an issue into smaller, more manageable tasks. It begins with the major issue and gradually breaks it down into related issues.
  • Modularity: Modularity is the concept of breaking a programme down into more manageable, standalone modules or functions. Each module may be written, tested, and maintained independently and completes a certain job.
  • Control structures: Control structures direct how a programme is executed. Sequence, selection, and iteration are the three fundamental control structures. The term "sequence" describes how assertions are carried out in a particular order. Decisions may be made depending on conditions thanks to selection. Iteration allows a block of code to be executed repeatedly.
  • Structured Data: Data that has been organised into structures like arrays, records, and objects is known as structured data. By representing complicated data interactions with the aid of these structures, programmes'readability and maintainability are enhanced.

Core Elements in Structured Programming:

A programming paradigm known as "structured programming" focuses on using structured control flow components to enhance the readability, effectiveness, and maintainability of code.

  •  Different categories of structured programming constructs include:
  • Sequence: As was already established, sequence denotes the execution of statements one after the other in a sequential order. It guarantees that all statements are performed consecutively throughout the code, without branching or duplication.
  • Selection: The programme may make decisions based on criteria thanks to selection structures. The "if-then-else" phrase is the most typical selection structure. Depending on whether a condition is true or not, it assesses it and decides which code blocks to run. Additional alternatives that offer many conditional branches include "switch" and "case" statements.
  • Repetition: Repetition structures, usually referred to as loops or iterations, allow a programme to repeatedly execute a single piece of code. There are two main categories of loops:
    • While loop: Repeatedly runs a section of code while a predetermined condition is true. Before each iteration, the condition is assessed, and the loop ends when the condition is no longer true.
    • For loop: runs a piece of code for a certain number of times. An initialization, a condition for the loop to continue, an increment or decrement operation, and the code block that will be run once for each iteration are the standard components of a for loop.

The fundamental building blocks of structured programming are sequence, selection, and repetition. They offer the capabilities required to manage the execution flow, make choices, and repeat activities depending on certain circumstances. Developers may design well-structured, modular, and maintainable programmes by successfully using these architectures.

Examples of Structured Programming

Different programming languages can be used to implement structured programming ideas. Some languages, nevertheless, are created explicitly to allow structured programming. Here are a few illustrations:

  • C Language: Structured programming is heavily supported by the widely used computer language C. It offers functions, while and for loops, if-else expressions, sequential execution, and modular programming, among other things.
  • Pascal: A high-level language designed primarily for teaching structured programming, Pascal was created in the 1970s. Through procedures and functions, it incorporates elements like repetition, sequence, selection, and modularization while enforcing the principles of structured programming.
  • Python: Python offers structured programming and is a flexible language. It provides building blocks for developers to organise their code in a systematic and legible way, including if-else expressions, for and while loops, functions, and modules.
  • Java: Java is yet another widely used language that applies the concepts of structured programming. It offers tools like if-else clauses, for and while loops, methods (functions), and classes that let programmers create organised, modular code.

An additional set of features for object-oriented programming or other paradigms can be included in languages that enable structured programming. However, programmers may write more understandable, manageable, and well-organized code by following the rules of structured programming.

Advantages of structured programming:

  • Readability and Maintainability: organised programming enhances code readability by grouping code into organised blocks and employing control structures like sequence, selection, and repetition.
  • Controlling the flow of a programme explicitly is made possible by structured programming, which uses constructs like if-else statements, loops, and function calls. This makes it possible for developers to successfully manage a variety of circumstances and settings.
  • Modularity and Code Reusability: Structured programming promotes the development of reused code components.
  • Error handling: Structured programming offers a systematic method for addressing errors. Developers can effectively handle and manage exceptions or problems that may arise during programme execution by employing control structures like try-catch blocks.

Disadvantages of structured programming:

  • Complexity: Certain complicated cases may not easily fit into a structured paradigm, despite the fact that structured programming offers a clear and organised method to programming.
  • Lack of Flexibility: The predetermined control mechanisms and strict structure of the structured programming paradigm make it less flexible.
  • Increased Code Length: Because control structures are explicitly represented and modularization is used, structured programming often results in larger code.
  • Limited Expressivity: Control flow and modularization are the main objectives of structured programming, which may have an impact on how expressive the code is.