Rust Functions

🦀 Rust Functions

They help make programs clean, modular, and readable.

1. Defining a Function

Syntax

• fn → function keyword

• Function names use snake_case

• Code block inside {}

 2. Function with Parameters

✔ Parameter types are mandatory

 3. Function with Return Value

Important

• -> i32 defines return type

• Last expression (without ;) is returned

• return keyword is optional

 4. Using return Keyword

✔ Useful for early returns

 5. Multiple Parameters

 6. Function as Expression

Functions can be used inside expressions.

 7. Function Scope

Functions can be defined outside main().

✔ Rust does not allow nested named functions

 8. Returning Multiple Values (Tuple)

 9. Function with Option

 10. Best Practices

✔ Use meaningful function names
✔ Keep functions small
✔ One function → one responsibility
✔ Use Option / Result for safety

🧠 Summary

• fn keyword defines function

• Types are mandatory for parameters

• Functions return values via expressions

• Encourages safe & clean code