G++ 4.6.3 Linux 中使用 quadmath 的四倍精度

Question

我已经尝试执行代码

#include <quadmath.h>
#include <iostream>
int main()
{
  char* y = new char[1000];
  quadmath_snprintf(y, 1000, "%Qf", 1.0q);
  std::cout << y << std::endl;
  return 0;
}

用这个命令

g++ test.cpp -o test

但我得到了错误：

/tmp/cctqto7E.o: In function `main':
test.cpp:(.text+0x51): undefined reference to `quadmath_snprintf(char*, unsigned int, char const*, ...)'
collect2: ld returned 1 exit status

版本是：

g++ --version
g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

我该如何解决这个问题？

Answer 1

我看到了同样的行为：

~/coding/q$ g++ test.cpp -lquadmath
/tmp/ccYdHwL5.o: In function `main':
test.cpp:(.text+0x51): undefined reference to `quadmath_snprintf(char*, unsigned int, char const*, ...)'
collect2: ld returned 1 exit status

一种解决方法是使用此模式包含标题：

extern "C" {
#include "quadmath.h"
}

之后：

~/coding/q$ g++ test.cpp -lquadmath
~/coding/q$ ./a.out 
1.000000