Question

我已经在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，我收到错误，说找不到fmin和fmax标识符。我安装了Windows SDK 7.1以查看是否能解决问题并且它什么也没做：/

#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功能。 Visual Studio仅实现C89标准，因此它没有这些功能。

Answer 2

由于它是C ++，你可以（而且，我敢说，应该）使用std::min标题中的std::max和<algorithm>函数。

这些是函数模板，因此它们将接受定义了比较运算符的任何类型。只需确保两个参数的类型相同，否则可能无法编译。

Visual C ++ Express：找不到fmin和fmax标识符？

2 个答案: