Function Parameters

Function parameters are like the ingredients you pass to a recipe - they're the values that a function needs to do its job! When you call a function, you can send it data through parameters, making your functions flexible and reusable.

Basic Syntax

return_type function_name(parameter_type parameter_name) {
    // function body
    return value; // if needed
}

Simple Example

Here's a function that takes two numbers and return the max number:

#include <stdio.h>

int findMaxNumber(int a, int b) {
    if(a > b){
      return a;
    } else {
      return b;
    }
}

int main() {
    int result = findMaxNumber(5, 3);
    printf("Result: %d\n", result);
    return 0;
}

In this example:

• a and b are parameters of the findMaxNumber function
• 5 and 3 are arguments passed when calling the function

Multiple Parameters

Functions can have multiple parameters of different types:

#include <stdio.h>

void displayInfo(char name[], int age, float height) {
    printf("Name: %s\n", name);
    printf("Age: %d years\n", age);
    printf("Height: %.1f cm\n", height);
}

int main() {
    displayInfo("Alice", 25, 165.5);
    return 0;
}

Parameter Types

Parameter Type	Description	Example
Value Parameters	Copies of the actual values	int x, float y
Array Parameters	Arrays passed by reference	int arr[]
Pointer Parameters	Memory addresses	int *ptr

Note: We will learn more about Pointers in upcoming topics.

Pass by Value

In C, most parameters are passed by value, meaning the function gets a copy of the data:

#include <stdio.h>

void modifyValue(int x) {
    x = 100;  // This only changes the copy
    printf("Inside function: %d\n", x);
}

int main() {
    int num = 50;
    modifyValue(num);
    printf("Outside function: %d\n", num);  // Still 50!
    return 0;
}

Functions with No Parameters

Sometimes functions don't need any input:

#include <stdio.h>

void sayHello(void) {  // 'void' means no parameters
    printf("Hello, World!\n");
}

int main() {
    sayHello();  // No arguments needed
    return 0;
}

Key Points to Remember

• Parameters are like variables that receive values from function calls
• The number and type of arguments must match the parameters
• Parameter names are local to the function
• Changes to parameters (pass by value) don't affect the original variables
• Use meaningful parameter names to make your code readable

Parameters make functions powerful and flexible - they're your gateway to writing reusable code that can work with different data each time it's called!