🔄 Loops in C++ (for, while, do-while) - Complete Notes

Video Reference: Loops in C++ by The Cherno | Full Playlist

1. 📌 Introduction to Loops

Timestamp: 00:00:00

• Purpose: Execute code repeatedly without rewriting it.
• Use Cases:
  • 🖨️ Print “Hello World” 5 times instead of copy-pasting.
  • 🎮 Game loops (continuous execution until user quits).

2. 🔢 For Loops

Timestamp: 00:02:00

Syntax:

for (initialization; condition; iteration) {  
    // Code to repeat  
}  

Example: Print “Hello World” 5 times

for (int i = 0; i < 5; i++) {  
    std::cout << "Hello World 🌍" << std::endl;  
}  

Breakdown:

1. 🚀 Initialization: int i = 0 (executes once at start).
2. ✅ Condition: i < 5 (checked before each iteration; loop continues if true).
3. 🔄 Iteration: i++ (executes after each iteration).

Key Points:

• 🎛️ Flexibility: All three parts (initialization, condition, iteration) can be modified.

  int i = 0;  
  for ( ; ; ) {  
      if (i >= 5) break;  
      std::cout << "Hello World 🌍" << std::endl;  
      i++;  
  }  
  

• ♾️ Endless Loop: Remove condition → for (;;) { ... }.

3. 🔄 While Loops

Timestamp: 00:07:24

Syntax:

while (condition) {  
    // Code to repeat  
}  

Example: Equivalent to the For Loop

int i = 0;  
while (i < 5) {  
    std::cout << "Hello World 🌍" << std::endl;  
    i++;  
}  

Use Case:

• 🎮 Game Loop:

  bool isRunning = true;  
  while (isRunning) {  
      UpdateGame();  
      RenderGraphics();  
  }  
  

4. ➰ Do-While Loops

Timestamp: 00:10:12

Syntax:

do {  
    // Code to execute at least once  
} while (condition);  

Example:

int i = 0;  
do {  
    std::cout << "Hello World 🌍" << std::endl;  
    i++;  
} while (i < 5);  

Key Difference:

• Executes the body at least once, even if the condition is initially false.

5. 📊 Key Differences

| Loop Type | When to Use | Notes |
|—————-|————————————–|————————————-|
| 🔢 For | Known number of iterations | Compact syntax for index-based loops |
| 🔄 While | Condition-based repetition | Flexible for dynamic conditions |
| ➰ Do-While| Execute code once before checking | Rarely used; specific edge cases |

6. 📝 Summary

• For Loops: Best for fixed iterations (e.g., arrays, counting).
• While Loops: Ideal for unknown iterations (e.g., game loops).
• ⚠️ Avoid Infinite Loops: Ensure the loop condition eventually becomes false.

Next Steps: Use loops with arrays (covered in future videos).

Need More Context? Jump to the full video for visual explanations. 🎥