Question

我试图在我的Objective-C项目中使用C函数，但我无法将它们混合使用。

我有以下功能：

// 1. Pass in the cost function which takes in an array and gives out cost and gradient at the given input.
// 2. xVector should contain the initial point which is will be modified to reflect the optimum point
// 3. nDim is the dimension of xVector
// 4. maxCostCalls is the maximum number of times the cost function may be called
// return value:  1 -> Num of Cost function calls exceeded max specified in the argument. 2-> line search failed

int fmincg(void (*costFunc)(double* inputVector, double* cost, double* gradVector), double* xVector, int nDim, int maxCostFuncCalls); xVector, int nDim, int maxCostFuncCalls);

这是我传递给第一个参数的函数：

static void _fmincg_evaluate(id thisClass, LKDataset *inputFeatures, LKFeature *outputFeature, LKMatrixObject *initialWeights, double cost, LKMatrixObject *optimizedWeights) {
    cost = [thisClass costUsingLogisticRegressionWithInputFeatures:inputFeatures outputFeature:outputFeature andWeights:initialWeights];
    optimizedWeights = [thisClass optimizeWeightsUsingGradientDescentForInputFeatures:inputFeatures outputFeature:outputFeature andWeights:initialWeights];
}

最后要调用fmincg，我会执行以下操作：

fmincg(_fmincg_evaluate(self, inputFeatures, outputFeature, self.weights, cost, optimizedWeights), inputFeatures->matrix, inputFeatures.elementCount, 50);

但是我收到以下错误：

传递＆＃39;无效＆＃39;到不兼容类型的参数＆＃39; void（*）（double *，double *，double *）＆＃39;

也许是因为睡眠不足，但我有点困惑，因为我是C的新手。

Answer 1

您正在尝试传递调用The documentation for this class was generated from the following file: *source/file1/doxyTest.cs函数的结果，而不是传递实际的_fmincg_evaluate函数。

你想：

_fmincg_evaluate

fmincg(_fmincg_evaluate, inputFeatures->matrix, inputFeatures.elementCount, 50);的实现将负责调用传入的函数指针及其所需的任何参数。

更新：正如Adrian在下面的评论中指出的那样，您不能将fmincg函数作为第一个参数传递给_fmincg_evaluate函数，因为参数类型不适用匹配。

将void传递给不兼容类型的参数？

1 个答案: