我想将C#字符串传递给C dll函数,该函数假设要对其进行加密。不幸的是,它什么都没做。调用函数后,字符串仍然是相同的。
C函数:
#include <stdio.h>
#include <stdlib.h>
extern "C"{
__declspec(dllexport) void Encrypt( char *plainText,long height,long inputLength)
{
unsigned char *encryptedText=(unsigned char*)malloc(sizeof(plainText));
unsigned char **cipherArray;
cipherArray=(unsigned char**)malloc(height*sizeof(unsigned char *));
for(long i=0; i<height; i++)
{
cipherArray[i]=(unsigned char*)malloc(inputLength*sizeof(char));
for (long j=0; j<inputLength ; j++)
cipherArray[i][j]='#';
}
bool addRow=true;
long row=0;
long column = 0;
long arrayIterator = 0;
while(arrayIterator<inputLength){
cipherArray[row][column] = plainText[arrayIterator];
column++;
if(addRow)row++;
else row--;
if (row >= height)
{
row--;
row--;
addRow=false;
}
else if (row < 0)
{
row++;
row++;
addRow = true;
}
arrayIterator++;
}
long iterator=0;
for (long i=0; i< height; i++)
for(long j=0; j<inputLength;j++){
if(cipherArray[i][j]!='#'){
encryptedText[iterator]=cipherArray[i][j];
iterator++;
}
}
long j=0;
while(j<inputLength){
plainText[j]=encryptedText[j];
printf("%c",encryptedText[j]);
j++;
}
for(long i=0; i<height; i++)
free(cipherArray[i]);
free(cipherArray);
cipherArray = NULL;
}
}
包含C#类:
namespace RailFenceCipher
{
public class CCipher
{
[DllImport("Win32Project3.dll", EntryPoint = "Encrypt", CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
public static extern void Encrypt([MarshalAs(UnmanagedType.LPStr)] string plainText, long height, long inputLength);
}
}
并要求该功能:
private void cipherC()
{
string plainText = this.fileInput;
Console.WriteLine("=== C# test, using IntPtr and Marshal ===");
CCipher.dllprint();
CCipher.Encrypt(plainText, this.height, this.fileInput.Length);
this.fileOutputC = plainText;
Console.WriteLine("=== END ===");
}
调用后,plainText不会更改。
答案 0 :(得分:2)
这是可以预料的。您正在编组数据,但不是。这是string类型参数的行为。您需要使用StringBuilder来从本机代码封送文本。
另外,C#long是64位,但C ++ long是32位。你的pinvoke应该是:
[DllImport("Win32Project3.dll", CallingConvention = CallingConvention.Cdecl,
CharSet = CharSet.Ansi)]
public static extern void Encrypt(StringBuilder plainText,
int height, int inputLength);
您需要确保传递的StringBuilder实例的容量足以返回文本。
也许更大的问题是您的C ++代码被破坏了。至少,您需要修复接收sizeof(plainText)的malloc调用。那是指针的大小。您需要传递缓冲区的长度inputLength。您应该在尝试互操作之前先调试该代码。