How the computer handles variables

parameters_is_value.c

#include <stdio.h>

void add(int a, int b) {
  a = a + b;
}

int main(void) {
  int a = 7;
  add(a, 10)
  
  // print: a = 7
  printf("%d\n", a);

  system("pause");
  return 0;
}