Flowcharts: An Introduction

A flowchart is a graphical representation of an algorithm or a process. It uses different shapes to represent different types of actions or steps, with arrows connecting them to show the flow of control or process. Flowcharts are widely used in programming, project planning, business processes, and systems design. They provide a clear, easy-to-understand view of a process or procedure, helping people visualize how a system works and identify areas for improvement.

Basic Flowchart Symbols

1. Oval (Start/End)
   • Represents the start and end of a process.
   • Symbol:
     • Start: Oval with the label “Start.”
     • End: Oval with the label “End.”
2. Rectangle (Process)
   • Represents a process or an action step (e.g., calculations, assignments).
   • Symbol: A rectangle with the action written inside.
3. Parallelogram (Input/Output)
   • Represents input or output operations, like taking user input or displaying a result.
   • Symbol: A parallelogram with “Input” or “Output” written inside.
4. Diamond (Decision)
   • Represents a decision point in the process where the flow can diverge based on a condition (yes/no or true/false).
   • Symbol: A diamond shape with the condition written inside.
5. Arrow (Flowline)
   • Represents the direction of flow in the process from one step to the next.
   • Symbol: A straight line with an arrowhead pointing to the next process.
6. Circle (Connector)
   • Used to connect different parts of the flowchart when it’s too large to fit on one page or when a continuation is needed.
   • Symbol: A small circle labeled with a letter or number to indicate the connection.

How to Read a Flowchart

Reading a flowchart involves following the flow from the Start symbol to the End symbol. You should move through the shapes according to the arrows, making decisions when you reach a diamond (decision) symbol. The flowchart’s logic will guide you through the steps, conditions, and processes that need to occur.

---

Example Flowcharts

1. Flowchart for Finding the Largest of Two Numbers

Let’s consider a simple algorithm to find the largest of two numbers. Here’s how the flowchart would look:

Steps:

1. Start
2. Input two numbers: num1 and num2
3. Compare num1 and num2
4. If num1 > num2, output num1 as the largest number
5. Else, output num2 as the largest number
6. End

Flowchart:

  [Start]
     |
     v
 [Input num1, num2]
     |
     v
  [num1 > num2?] ---- No ----> [Output num2]
     |
    Yes
     |
     v
  [Output num1]
     |
     v
   [End]

---

2. Flowchart for Calculating the Factorial of a Number (n!)

Steps:

1. Start
2. Input a number n
3. Initialize factorial = 1
4. Check if n > 1
5. If n > 1, multiply factorial = factorial × n and decrease n by 1.
6. Repeat the process until n = 1
7. Output the factorial
8. End

Flowchart:

  [Start]
     |
     v
 [Input n]
     |
     v
[Initialize factorial = 1]
     |
     v

[n > 1?]

/ \ Yes No / \ v v [factorial = factorial × n] [Output factorial] | v

[n = n – 1]

| v [n > 1?] (Repeat until No) | v [End]

---

3. Flowchart for a Simple Login System

A more complex example involves a decision process for verifying user credentials in a login system.

Steps:

1. Start
2. Input username and password
3. Check if the username and password match the stored values
4. If they match, display “Login successful” and end
5. If they don’t match, display “Login failed” and ask for credentials again or end
6. End

Flowchart:

  [Start]
     |
     v
[Input username, password]
     |
     v
[Check username and password]
     |
     v
 [Match?]
   /    \
  Yes    No
  /       \
 v         v
[Login     [Display "Login failed"]
 successful]
     |
     v
   [End]

---

When to Use Flowcharts

1. Algorithm Design:
   Flowcharts are helpful when designing algorithms, as they allow you to visualize the logic and steps involved. This makes it easier to break down complex processes and communicate them to others.
2. Troubleshooting & Debugging:
   When debugging software or analyzing a process, flowcharts can be used to trace the flow of the program or system. This helps identify where things go wrong.
3. Process Documentation:
   Flowcharts are commonly used in business process management to document workflows. They provide a clear, easy-to-understand diagram of how tasks should flow in a business process or system.
4. Teaching and Learning:
   For beginners in programming, flowcharts can help in understanding the logical flow of algorithms and processes before they write the actual code.

---

Advantages of Flowcharts

• Clarity: Flowcharts make complex processes easy to understand by visually breaking down each step.
• Communication: They provide an effective way to communicate ideas, especially in teams or when presenting a concept to non-technical audiences.
• Problem-solving: By mapping out the entire process, flowcharts help identify areas that need improvement or optimization.
• Documentation: Flowcharts serve as excellent documentation tools for both new and existing systems.

Disadvantages of Flowcharts

• Scalability: Large systems can result in very complex flowcharts that are difficult to manage and read.
• Limited Detail: Flowcharts often lack the level of detail that is required for a full technical implementation, so they must be supplemented with other documentation (like pseudo-code).
• Time-consuming: Drawing flowcharts can be time-consuming, especially for larger, more complex algorithms.

---

Conclusion

Flowcharts are a simple yet powerful tool for illustrating algorithms and processes. By using standard symbols to represent actions, decisions, and inputs/outputs, they provide a clear and structured way to visualize logic and workflows. Whether you’re designing software, documenting business processes, or simply explaining a procedure, flowcharts are a valuable resource in both education and professional work.

If you’re ever unsure about how to approach a problem or design a system, creating a flowchart is a great first step!