Algorithm & Flowcharting

Algorithm = The step-by-step plan (like a recipe).

Flowchart = A simple drawing of that plan using shapes.

💡 Think of building a house:
You don’t start laying bricks without a plan.
Similarly, programmers don’t write code without an algorithm or flowchart!

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✏️ 1. What is an Algorithm in Software?

An algorithm is a clear list of instructions that tells the computer what to do to solve a problem or run a software feature.

Example: A "Login" Feature in an App

Algorithm for Login:

1. Start
2. Show username and password boxes
3. User types username and password
4. Click "Login" button
5. Check if username and password are correct
6. If correct → Open the home screen
7. If wrong → Show "Invalid login" message
8. Stop

✅ This algorithm helps the programmer know exactly what code to write.

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🖼️ 2. What is a Flowchart in Software?

A flowchart is a visual plan of the software’s logic using standard shapes. It helps developers (and even non-tech people) see how the software will work.

Common Symbols Used in Software Flowcharts

Shape	Name	Use in Software
🟢 Oval	Start / Stop	Beginning or end of a feature (e.g., "Start Login")
🟦 Rectangle	Process	Actions like "Check password", "Save data"
🟨 Parallelogram	Input / Output	Getting user input ("Enter email") or showing output ("Welcome!")
🔺 Diamond	Decision	Yes/No questions like "Is password correct?"
➡️ Arrow	Flow	Shows the order of steps

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🧩 3. Real Software Examples (Simple!)

Example 1: Calculator App – Adding Two Numbers

Algorithm:

1. Start
2. Show two input boxes for numbers
3. User enters Number A and Number B
4. Click “Add” button
5. Calculate Sum = A + B
6. Display the result
7. Stop

Flowchart:

[Start]  
   ↓  
[Show input boxes]  
   ↓  
[User enters A and B]  
   ↓  
[Click Add]  
   ↓  
[Sum = A + B]  
   ↓  
[Display Sum]  
   ↓  
[Stop]

💻 This is how a simple calculator app is planned before coding!

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Example 2: Weather App – Show Message Based on Temperature

Algorithm:

1. Start
2. Get today’s temperature from internet
3. If temperature > 30°C → Show “It’s hot! Drink water.”
4. Else → Show “Nice weather!”
5. Stop

Flowchart:

[Start]  
   ↓  
[Get temperature]  
   ↓  
{Is temp > 30?}  
   ↙️ (Yes)                ↘️ (No)  
[Show "Hot!"]         [Show "Nice!"]  
   ↘️                      ↙️  
        [Stop]

🌤️ This flowchart helps the app make smart decisions!

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✅ Why Are They Important in Software?

Benefit	Explanation
Clear Planning	Developers know what to build before writing code
Fewer Mistakes	Logic errors are caught early (saves time & money)
Team Work	Designers, testers, and managers can understand the plan
Easy to Improve	You can change the flowchart before coding starts
Used in Exams & Interviews	Shows your problem-solving skills

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❌ Common Mistakes in Software Flowcharts

• Forgetting the Start and Stop
• Using a rectangle for a question (use diamond instead!)
• Not labeling Yes/No on decision arrows
• Making the flow too complex (break big software into small parts!)

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📚 Quick Summary

Tool	Role in Software Development
Algorithm	Written plan of steps → turns into code
Flowchart	Picture of the plan → helps everyone understand

🔁 Process:
Problem → Algorithm → Flowchart → Code → Working Software