c++ - Visual C++ Express : fmin and fmax identifier not found?

Question

我在 Mac 上编译了这段代码，所以我知道没有语法错误，但是，在 VC++ Express 2010 中，我收到一条错误消息，指出找不到 fmin 和 fmax 标识符。我安装了 Windows SDK 7.1 以查看是否可以修复它，但它什么也没做:/

#include "DigitalDistortion.h"
#include "IPlug_include_in_plug_src.h"
#include "IControl.h"
#include "resource.h"

const int kNumPrograms = 1;

enum EParams
{
  kThreshold = 0,
  kNumParams
};

enum ELayout
{
  kWidth = GUI_WIDTH,
  kHeight = GUI_HEIGHT,

  kThresholdX = 100,
  kThresholdY = 100,
  kKnobFrames = 60
};

DigitalDistortion::DigitalDistortion(IPlugInstanceInfo instanceInfo)
  :     IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), mThreshold(1.)
{
  TRACE;

  //arguments are: name, defaultVal, minVal, maxVal, step, label
  GetParam(kThreshold)->InitDouble("Threshold", 100., 0.01, 100.0, 0.01, "%");
  GetParam(kThreshold)->SetShape(2.);

  IGraphics* pGraphics = MakeGraphics(this, kWidth, kHeight);
  pGraphics->AttachPanelBackground(&COLOR_RED);

  IBitmap knob = pGraphics->LoadIBitmap(KNOB_ID, KNOB_FN, kKnobFrames);

  pGraphics->AttachControl(new IKnobMultiControl(this, kThresholdX, kThresholdY,         kThreshold, &knob));

  AttachGraphics(pGraphics);

  //MakePreset("preset 1", ... );
  MakeDefaultPreset((char *) "-", kNumPrograms);
}

DigitalDistortion::~DigitalDistortion() {}

void DigitalDistortion::ProcessDoubleReplacing(
    double** inputs,
    double** outputs,
    int nFrames)
{
  // Mutex is already locked for us.

  int const channelCount = 2;

  for (int i = 0; i < channelCount; i++) {
    double* input = inputs[i];
    double* output = outputs[i];

    for (int s = 0; s < nFrames; ++s, ++input, ++output) {
      if(*input >= 0) {
        // Make sure positive values can't go above the threshold:
        *output = fmin(*input, mThreshold);
      } else {
        // Make sure negative values can't go below the threshold:
        *output = fmax(*input, -mThreshold);
      }
      *output /= mThreshold;
    }
  }
}

void DigitalDistortion::Reset()
{
  TRACE;
  IMutexLock lock(this);
}

void DigitalDistortion::OnParamChange(int paramIdx)
{
  IMutexLock lock(this);

  switch (paramIdx)
  {
    case kThreshold:
      mThreshold = GetParam(kThreshold)->Value() / 100.;
      break;

    default:
      break;
  }
}

Answer 1

fmin 和 fmax 是 C99 特性。 Visual Studio 只实现了 C89 标准，所以它没有那个功能。