C ++ std :: partition编译错误

Question

我正在尝试对数组进行分区以进行快速排序。 由于在分区部分出现编译错误，因此我没有对其进行完整的编码。 我不确定该如何处理错误列表。

这是加权结构的标头

#ifndef WEIGHTED_POINT_H
#define WEIGHTED_POINT_H

struct WeightedPoint {

    _int64 pointWeight;
    int xCoordinate;
    int ycoordinate;

};

bool compareWeightedPoints(WeightedPoint p1, WeightedPoint p2);

#endif

这是它的CPP

#include "WeightedPoint.hpp"

bool compareWeightedPoints(WeightedPoint p1, WeightedPoint p2) {
    return p1.pointWeight < p2.pointWeight;
}

这是主要方法

#include <algorithm>
#include <vector>

#include "WeightedPoint.hpp"

const int VECTOR_SIZE = 100;

WeightedPoint* partitionWeightedPoints(WeightedPoint* first, WeightedPoint* last) {

    WeightedPoint* key = first;
    WeightedPoint* middle = std::partition(first + 1, last, [=](const WeightedPoint *data)->bool {return data->pointWeight < key->pointWeight; }) - 1;

}

void fillWeightedPointsVector(std::vector<WeightedPoint> inputData) {

    int counter = 0;
    while (counter++ < VECTOR_SIZE) {
        inputData.push_back({ std::rand(), std::rand(), std::rand() });
    }

}

int main() {

    std::vector<WeightedPoint> inputData;
    fillWeightedPointsVector(inputData);
    WeightedPoint* arrayToSort = inputData.data();
    int numberOfElements = inputData.size();
    partitionWeightedPoints(&arrayToSort[0], &arrayToSort[numberOfElements - 1]);
}

这是编译错误

1>------ Build started: Project: TestPartition, Configuration: Debug Win32 ------
1>  WeightedPoint.cpp
1>  MainSource.cpp
1>c:\program files (x86)\microsoft visual studio 12.0\vc\include\algorithm(2141): error C2664: 'bool partitionWeightedPoints::<lambda_a5c326daa6382dcb3f8cf628cbfa8999>::operator ()(const WeightedPoint *) const' : cannot convert argument 1 from 'WeightedPoint' to 'const WeightedPoint *'
1>          No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
1>          c:\program files (x86)\microsoft visual studio 12.0\vc\include\algorithm(2164) : see reference to function template instantiation '_BidIt std::_Partition<_Iter,_Pr>(_BidIt,_BidIt,_Pr,std::bidirectional_iterator_tag)' being compiled
1>          with
1>          [
1>              _BidIt=WeightedPoint *
1>  ,            _Iter=WeightedPoint *
1>  ,            _Pr=partitionWeightedPoints::<lambda_a5c326daa6382dcb3f8cf628cbfa8999>
1>          ]
1>          c:\users\gopalmenon\documents\visual studio 2013\projects\testpartition\testpartition\mainsource.cpp(11) : see reference to function template instantiation '_FwdIt std::partition<WeightedPoint*,partitionWeightedPoints::<lambda_a5c326daa6382dcb3f8cf628cbfa8999>>(_FwdIt,_FwdIt,_Pr)' being compiled
1>          with
1>          [
1>              _FwdIt=WeightedPoint *
1>  ,            _Pr=partitionWeightedPoints::<lambda_a5c326daa6382dcb3f8cf628cbfa8999>
1>          ]
1>c:\program files (x86)\microsoft visual studio 12.0\vc\include\algorithm(2146): error C2664: 'bool partitionWeightedPoints::<lambda_a5c326daa6382dcb3f8cf628cbfa8999>::operator ()(const WeightedPoint *) const' : cannot convert argument 1 from 'WeightedPoint' to 'const WeightedPoint *'
1>          No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
1>  Generating Code...
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

我不确定该怎么做。 我不太擅长C ++。 任何帮助将非常感激。

Answer 1

std::partition期望谓词采用const引用（在这种情况下，即const WeightedPoint& ），但是您的谓词签名采用const指针。 这是您当前的编译错误出处。 要删除它，例如更改

[=](const WeightedPoint *data)->bool {return data->pointWeight < key->pointWeight; }

至

[=](const WeightedPoint& data)->bool {return data.pointWeight < key->pointWeight; }