c ++ indefinite parameters

Define the variable parameters, use macros are:

va_start (ap, arg) to initialize a variable of the va_list ap

va_arg (ap, type) Get the next type of parameter type

va_end (ap) finished using ap

#include <stdarg.h>
#include <stdio.h>

int sum(int cnt, ...) {
  int sum = 0;
  va_list ap;
  va_start(ap, cnt);
  for (int i = 0; i < cnt; ++i) {
    sum += va_arg(ap, int);
  }
  va_end(ap);
  return sum;
}

int main() {
  int result = sum(3, 1, 2, 3);
  printf("the result is %d\n", result);
  return 0;
}

It is output: the result is 6