c – 为什么三元运算符中的多个语句未执行

参见英文答案 > Undefined behavior and sequence points????????????????????????????????????5个
>???????????? What’s the precedence of comma operator inside conditional operator in C++?????????????????????????????????????3个
我对以下内容感到困惑：

#include <iostream>

int main()
{
  bool a = true;
  int nb = 1;
  int nb2 = 2;
  a ? nb++,nb2++ : nb--,nb2--;
  std::cout << " (nb,nb2) = (" << nb << "," << nb2 << ")";
}

结果：

(nb,nb2) = (2,2)

为什么nb2不等于3？

((a) ? (nb++,nb2++) : nb--),nb2--;