用0开头的数字[重复]

可能重复:
Print leading zeros with C++ output operator (printf equivalent)?

#include <iostream>
#include <iomanip>
int main()
{
   int n = 16;
   std::cout << ???(5) << n << std::endl;
}

我希望输出是 00016
setw() 设置() ?

我的最终目标是在4个位置打印一个十六进制2字节数。像这样的:

#include <iostream>
#include <iomanip>
int main()
{
    unsigned short n = 0xA7;
    std::cout << std::hex << ???(4) << n << std::endl;
}

00A7