Question

现在，我已经将python称为C ++。使用ctype在两者之间进行连接。而且我在运行时遇到有关核心转储的问题。

我有一个名为“ libfst.so”的库这是我的代码。 NGramFST.h

#include "NGramFST.h"
NGramFST* NGramFST::m_Instace = NULL;

extern "C" {
    double FST_getProbability(std::string word, std::string context){
        return NGramFST::getInstance()->getProbabilityOfWord(word, context);
    }
}

NGramFST.cpp

from ctypes import cdll
lib = cdll.LoadLibrary('./libfst.so')

#-------------------------main code------------------------
class FST(object):
    def __init__(self):
        print 'Initializing'

    def getProbabilityOfWord(self, word, context):
        lib.FST_getProbability(word, context)

fst = FST()
print fst.getProbabilityOfWord(c_wchar_p('jack london'), c_wchar_p('my name is'))

这是我的python代码。

terminate called after throwing an instance of 'std::bad_alloc'
  what():  std::bad_alloc
Aborted (core dumped)

这是错误

Public Sub TransformToColumnsByAcct()
    Dim rngSrcData As Range, i As Long, objDict As Scripting.Dictionary, strKey As String, arrRows As Variant
    Dim lngHeaderStartCol As Long, x As Long, lngSrcRow As Long, lngWriteRow As Long, lngMaxUbound As Long

    Set rngSrcData = Selection
    Set objDict = New Scripting.Dictionary

    With rngSrcData
        ' Get all of the unique accounts, this will also determine for us the amount of columns we need to provide for.
        ' Start from the 2nd row because the 1st contains the header.
        For i = 2 To .Rows.Count
            strKey = .Cells(i, 1)

            If Not objDict.Exists(strKey) Then
                objDict.Add strKey, Array(i)
            Else
                arrRows = objDict.Item(strKey)
                ReDim Preserve arrRows(UBound(arrRows) + 1)
                arrRows(UBound(arrRows)) = i

                objDict.Item(strKey) = arrRows

                If UBound(arrRows) > lngMaxUbound Then
                    lngMaxUbound = UBound(arrRows)
                End If
            End If
        Next

        ' Clear all of the cells in the destination worksheet.
        shTransformed.Cells.Clear

        ' Add the header for the key field.
        shTransformed.Cells(1, 1) = .Cells(1, 1)

        lngHeaderStartCol = 2

        ' Now get all of the column headers excluding the first as this contains the key and write them to the
        ' transformed worksheet.  Dynamically increment the 2nd header by 1 each time.
        For i = 1 To lngMaxUbound + 1
            ' Determine the start column for the header to be copied to factoring in the first field.
            If i > 1 Then
                lngHeaderStartCol = lngHeaderStartCol + .Columns.Count - 1
            End If

            .Range(.Cells(1, 2).Address & ":" & .Cells(1, .Columns.Count).Address).Copy shTransformed.Cells(1, lngHeaderStartCol)

            ' Incremement the header text by 1 and put an underscore.
            shTransformed.Cells(1, lngHeaderStartCol) = shTransformed.Cells(1, lngHeaderStartCol) & "_" & i
        Next

        ' Now write out all of the unique keys to the transformed sheet along with the data.
        For i = 0 To objDict.Count - 1
            strKey = objDict.Keys(i)
            arrRows = objDict.Item(strKey)

            lngWriteRow = i + 2

            ' Write the key to the first column.
            shTransformed.Cells(lngWriteRow, 1) = strKey

            lngHeaderStartCol = 2

            ' Now process each row of data for the unique key.
            For x = 0 To UBound(arrRows)
                lngSrcRow = arrRows(x)

                If x > 0 Then
                    lngHeaderStartCol = lngHeaderStartCol + .Columns.Count - 1
                End If

                ' Copy the data for the given row to the transformed sheet.
                .Range(.Cells(lngSrcRow, 2).Address & ":" & .Cells(lngSrcRow, .Columns.Count).Address).Copy shTransformed.Cells(lngWriteRow, lngHeaderStartCol)
            Next
        Next
    End With
End Sub

我再次进行了审查，但我无法发现问题所在。

Answer 1

ctypes不了解C ++类型（未称为c++types）。它无法处理std::string。仍然不知道您的函数是否期望std::string自变量。

为了使用ctypes，您的库需要一个C兼容的接口。 extern "C"是必要的，但还不够。这些函数实际上必须可以从C调用。

更好的方法是使用现代的C ++ / Python绑定库，例如pybind11。

Answer 2

当我在下面更改python代码时就可以使用

string1 = "my string 1"
string2 = "my string 2"

# create byte objects from the strings
b_string1 = string1.encode('utf-8')
b_string2 = string2.encode('utf-8')

print fst.getProbabilityOfWord(b_string1, b_string2)

和c ++代码更改以下参数的类型

FST_getProbability(const char* word, const char* context)

内存核心转储C ++

2 个答案: