ios - Objective-C:单步执行 double* 数组时 EXC_BAD_ACCESS code=2

Question

在我的 init 中，我设置了以下内容:

- (id)init
{
    if (self = [super init])
    {
        // Time-Domain Wavelet pitch detection setup
        self.bufferCapacity = 2048;
        self.index = 0;
        dataBuffer = (SInt16*)malloc(self.bufferCapacity * sizeof(SInt16));
        dywapBuffer = (double*)malloc(self.bufferCapacity * sizeof(double));
        dywapitch_inittracking(&pitchtracker);
    }
    return self;
}

在回调中，我尝试执行以下操作:

    SInt16 *dataBuffer = THIS->dataBuffer;
    double *dywapBuffer = THIS->dywapBuffer;
    for (int i = 0; i < THIS.bufferCapacity; i++)
    {
        double* doublePointer = dywapBuffer + (i * sizeof(double));
        SInt16* intPointer = dataBuffer + (i * sizeof(SInt16));
        *doublePointer = (double)(*intPointer);
    }
    double frequency = dywapitch_computepitch(&THIS->pitchtracker, dywapBuffer, 0, frames);

但是，当 for 循环达到 i = 256 时，应用程序在尝试分配 doublePointer 时会崩溃，并显示 EXC_BAD_ACCESS code=2。任何人都知道我在这里做错了什么？我很难过。

Answer 1

试试这个

SInt16 *dataBuffer = THIS->dataBuffer;
double *dywapBuffer = THIS->dywapBuffer;
for (int i = 0; i < THIS.bufferCapacity; i++)
{
    // compiler will do the pointer arithmetic correctly for you
    double* doublePointer = dywapBuffer + i;
    SInt16* intPointer = dataBuffer + i;
    *doublePointer = (double)(*intPointer);
}
double frequency = dywapitch_computepitch(&THIS->pitchtracker, dywapBuffer, 0, frames);

你不需要像 dywapBuffer + (i * sizeof(double)) 这样的东西，因为它没有意义。编译器知道 dywapBuffer 的类型是 double *，所以 dywapBuffer + 1 会将地址增加 sizeof(double).