C language variable function understanding exercise va_args

When we use va_arg (ap, type ) to take out a parameter, about the type in va_arg: 

https://blog.csdn.net/major2007/article/details/6224515

https://www.cnblogs.com/shiweihappy/p/4246442.html

1. Error code 

void fun(int a, ...)
{
	int len, n;
	int arg;
	va_list args;
	va_start(args, a);
	//len = strlen(a);
	arg = va_arg(args, char);
	printf("n=%d, arg = %d\n", n, arg);

	arg = va_arg(args, int);
	printf("n=%d, arg = %d\n", n, arg);

	arg = va_arg(args, int);
	printf("n=%d, arg = %d\n", n, arg);

	arg = va_arg(args, int);
	printf("n=%d, arg = %d\n", n, arg);

	arg = va_arg(args, int);
	printf("n=%d, arg = %d\n", n, arg);

	printf("len=%d,n=%d\n", len, n);
	va_end(args);
}

int main()
{
	int a = 1;
	int b = 2;
	int c = 3;
	int d = 4;
	fun(a, b, c, d);

	return 0;
}

1.1 Incorrect results 

1.2 The cause of the error, the types must be consistent when parsing variable parameters

2. Correct code: 

void fun(int a, ...)
{
	int len, n;
	int arg;
	va_list args;
	va_start(args, a);
	//len = strlen(a);
	arg = va_arg(args, int);
	printf("n=%d, arg = %d\n", n, arg);

	arg = va_arg(args, int);
	printf("n=%d, arg = %d\n", n, arg);

	arg = va_arg(args, int);
	printf("n=%d, arg = %d\n", n, arg);

	arg = va_arg(args, int);
	printf("n=%d, arg = %d\n", n, arg);

	arg = va_arg(args, int);
	printf("n=%d, arg = %d\n", n, arg);

	printf("len=%d,n=%d\n", len, n);
	va_end(args);
}

int main()
{
	int a = 1;
	int b = 2;
	int c = 3;
	int d = 4;
	fun(a, b, c, d);

	return 0;
}

2.2 Correct result