C Function Parameters

C Function Parameters

Function parameters in C language are variables used to receive values from the function call.
They allow functions to work with different data each time they are called.

What Are Function Parameters?

Parameters are inputs to a function.

Example

Here, x is a parameter.

Parameters vs Arguments (Important)

 Function with Single Parameter

 Function with Multiple Parameters

•  Parameters are separated by commas

 Call by Value (Default in C)

 Definition

• Copy of variable is passed

• Changes do not affect original variable

•  Safe but cannot modify original value

 Call by Reference (Using Pointers)

 Definition

• Address of variable is passed

• Changes affect original variable

•  Used when function must modify data

 Array as Function Parameter

Arrays are always passing by reference.

•  No copy of array is make

Structure as Function Parameter

Call by Value

Call by Reference (Preferred)

•  Faster & memory efficient

Function Pointer as Parameter (Advanced)

•  Used in callbacks

 Default Parameters (Not in C)

•  C does not support default parameters
•  Use function overloading alternative or wrappers

 Variable Number of Parameters (Advanced)

•  Used in printf()

 Common Mistakes

•  Forgetting & in call by reference
•  Parameter & argument type mismatch
•  Array size confusion
•  Modifying data unintentionally

 Interview Questions (Must Prepare)

1. What are function parameters?

2. Difference between parameter & argument

3. Call by value vs call by reference

4. How arrays are pass to functions?

5. Can function return multiple values?

6. What are variable arguments?

 Real-Life Use Cases

• Data processing

• Modular programming

• Embedded systems

• APIs & libraries

• Callbacks & handlers

Summary

•  Parameters pass data to functions
•  C uses call by value by default
•  Use pointers for call by reference
•  Arrays are pass by reference
•  Essential for DSA & interviews