我正在尝试将字符串从C#传递给C ++ dll。我在dll中收到的字符串是一些奇怪的字符。这是我的代码。
在C ++中:dll:
#include "stdafx.h"
#include <tlhelp32.h>
#include <tchar.h>
#include "ProcessCheckerDll.h"
#include <fstream>
#include <algorithm>
#include <iostream>
#include <stdio.h>
#include <psapi.h>
#include "Shlwapi.h"
#include <string>
#include <windows.h>
namespace ProcessCheck
{
string GetRunningProcessFromHierarchy(char* argStrRoot)
{
char ch;
printf("Reached here 1.");
scanf_s("%c",&ch);
std::string strRoot(argStrRoot,strlen(argStrRoot));
printf_s("strRoot = %s",strRoot);
std::ifstream input("d:\\filelist.txt");
std::string line;
printf("Reached here 2.");
scanf_s("%c",&ch);
//printf("cdsroot=%ls",strRoot);
std::transform(strRoot.begin(), strRoot.end(), strRoot.begin(), ::tolower);
std::vector<std::string> collection;
string result="";
printf("Reached here 3.");
scanf_s("%c",&ch);
HANDLE hProcessSnap=nullptr;
HANDLE hProcess;
PROCESSENTRY32 pe32;
DWORD dwPriorityClass;
while( std::getline( input, line ) )
{
//Get the file name from path
std::wstring strPathFromTextFile = std::wstring(line.begin(), line.end());
LPCWSTR absolutePathToFile = strPathFromTextFile.c_str();
LPCWSTR onlyFileName = PathFindFileName(absolutePathToFile);
// Take a snapshot of all processes in the system.
hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
if(hProcessSnap == INVALID_HANDLE_VALUE)
{
printf("Failed to get the snapshot of running processes");
return result;
}
pe32.dwSize = sizeof(PROCESSENTRY32);
// Retrieve information about the first process and exit if unsuccessful
if(!Process32First(hProcessSnap, &pe32))
{
printf("Failed to get the first process from the list");
CloseHandle(hProcessSnap); // clean the snapshot object
return result;
}
// Now walk the snapshot of processes, and display information about each process in turn
do
{
LPCWSTR processFileName = pe32.szExeFile;
if(lstrcmpi(onlyFileName,processFileName)==0)
{
//If file name is same, check if path starts with cdsroot
HANDLE processHandle = NULL;
TCHAR filePath[MAX_PATH];
processHandle = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, FALSE, pe32.th32ProcessID);
if (processHandle != NULL)
{
if (GetModuleFileNameEx(processHandle, NULL, filePath, MAX_PATH) == 0)
{
printf("\nFailed to get module filename.");
}
else
{
std::wstring w_str(filePath);
std::string absolutePath(w_str.begin(), w_str.end());
std::transform(absolutePath.begin(), absolutePath.end(), absolutePath.begin(), ::tolower);
printf_s("Absolute path = %s", absolutePath);
printf_s("Matching with cdsroot = %s",strRoot);
if(absolutePath.find(strRoot)==0)
{
std::wstring processName(processFileName);
std::string strProcess(processName.begin(),processName.end());
printf_s("\nROOT match for Process name = %s",strProcess);
if (std::find(collection.begin(), collection.end(), strProcess) == collection.end())
{
collection.push_back(strProcess);
printf_s("\nAdding to collection Process name = %s",strProcess);
result = result + strProcess + ";";
}
}
}
CloseHandle(processHandle);
}
else
{
printf("\nFailed to open process.");
}
}
}
while(Process32Next(hProcessSnap, &pe32));
}
CloseHandle(hProcessSnap);
printf("Returning result %s", result);
scanf_s("%c",&ch);
return result;
}
}
头文件包含:
#include <stdexcept>
#include <vector>
using namespace std;
namespace ProcessCheck
{
extern "C" { __declspec(dllexport) string GetRunningProcessFromHierarchy(char* argStrRoot); }
}
C#中的代码是:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;
namespace ProcCheckTest
{
class Program
{
[DllImport("C:\\Users\\himanshu\\Documents\\Visual Studio 2012\\Projects\\ProcessCheck\\Release\\ProcessCheckerDll.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern string GetRunningProcessFromHierarchy([MarshalAs(UnmanagedType.LPStr)] string strRoot);
static void Main(string[] args)
{
string strRoot = "C:\\test\\today_16.6";
string returnValue = GetRunningProcessFromHierarchy(strRoot);
}
}
}
我传递的字符串是&#34; C:\ test \ today_16.6&#34;但是当我在dll代码中打印相同内容时,会打印出奇怪的字符。 这有什么不对?
答案 0 :(得分:2)
主要问题似乎在这里:
printf_s("strRoot = %s",strRoot);
问题是strRoot
的类型为std::string
,但格式字符串需要char*
。将其更改为:
printf_s("strRoot = %s",strRoot.c_str());
或直接使用argStrRoot
。
您的另一个问题是该函数的返回值。目前您返回std::string
。你不能用p / invoke编组。您需要返回char*
。更重要的是,现在,编组人员会在它收到的指针上调用CoTaskMemFree
作为返回值。因此,您需要使用char*
分配返回的CoTaskMemAlloc
。