Function Parameters

Functions get data through parameters. You pass in values (called arguments), and the function works with its own copies. Let's break down how this works.

Parameters vs Arguments

The parameter is the variable in the function definition. The argument is the actual value you pass when calling the function. Two sides of the same handshake.

#include 
void printInfo(char name[], int age) {
  printf("%s is %d years old\n", name, age);
}
int main() {
  printInfo("Alice", 25);
  printInfo("Bob", 30);
  return 0;
}
    

Pass by Value

C uses pass by value. The function gets a copy of the argument, not the original. Changing the parameter inside the function won't affect the original variable.

#include 
void changeValue(int x) {
  x = 100;
  printf("Inside function: %d\n", x);
}
int main() {
  int num = 5;
  changeValue(num);
  printf("Outside function: %d\n", num);
  return 0;
}
    

Multiple Parameters

You can pass as many parameters as you need. Separate them with commas in both the definition and the call.

#include 
double average(double a, double b, double c) {
  return (a + b + c) / 3.0;
}
int main() {
  double avg = average(10.5, 20.0, 15.5);
  printf("Average: %.2f\n", avg);
  return 0;
}