C Inline Function

⚡ C Inline Function Tutorial

An inline function in C language is a function where the compiler replaces the function call with the actual function code to reduce function call overhead.

👉 Mainly used for small, frequently called functions.

1️⃣ Why Inline Functions?

✔ Faster execution
✔ Removes function call overhead
✔ Useful in performance-critical code
✔ Common in embedded & system programming

2️⃣ What is `inline` in C?

The inline keyword is a request to the compiler, not a command.
The compiler may ignore it if:

Function is too large
Contains loops/recursion
Address of function is used

3️⃣ Basic Syntax

4️⃣ Simple Inline Function Example

✔ Faster than normal function call
✔ Best for small logic

5️⃣ Inline Function with `static` (Best Practice ⭐)

📌 static inline avoids multiple definition errors
📌 Very common in header files

6️⃣ Inline vs Macro (`#define`) ⭐

Feature	Inline Function	Macro
Type checking	✅ Yes	❌ No
Debugging	Easy	Hard
Side effects	Safe	Dangerous
Recommended	✅ Yes	❌ No

Macro Problem Example ❌

Inline Solution ✅

7️⃣ Inline with Header Files 🔥

math_utils.h

✔ Avoids function call overhead
✔ Used in standard libraries

8️⃣ Limitations of Inline Functions ❌

❌ Not suitable for large functions
❌ Cannot be recursive
❌ Increases binary size
❌ Compiler may ignore inline

9️⃣ Inline vs Normal Function

Feature	Inline	Normal
Speed	Faster	Slower
Memory	More	Less
Debugging	Hard	Easy
Best for	Small code	Large logic

🔟 Interview Questions (Must Prepare)

What is inline function?
Is inline a command or request?
Difference between macro & inline
Why static inline is used?
Can recursive function be inline?

🔥 Real-Life Use Cases

Embedded systems
Math libraries
Device drivers
Performance-critical loops
Header-only libraries

✅ Summary

✔ Inline functions improve performance
✔ Best for small functions
✔ Safer than macros
✔ Important for system-level programming

C Inline Function