Getting invalid conversion from 'char' to 'const char*' [-fpermissive] error - c++

Question

I'm trying to compare the first character of a string to see if it matches and if it does, I want to set the clipboard data. The string comes from the getclipboard function and set to const char* data and I have tried to set it to std::string but I get a different error from that.
Here is my Clipboard.cpp
#include <iostream>
#include <windows.h>
#include <cstring>
namespace Diall_ClipBoard_catch
{
class ClipBoard
{
private:
::HANDLE dHDat;
::std::string tmpstringsign;
bool isopen;
char* dHbuffer;
char* dHbuffertemp;
char* dNtoken;
public:
ClipBoard(void)
{
this->dHbuffer = const_cast <char*>("");
this->dHbuffertemp = const_cast <char*>("");
this->tmpstringsign = "dnb_4554_2102";
this->isopen = false;
};
~ClipBoard(void)
{
}
char* GetData(void)
{
this->Start();
if (this->isopen)
{
this->dHDat = ::GetClipboardData(CF_TEXT);
if (this->dHDat)
{
this->dHbuffer = (char*)::GlobalLock(this->dHDat);
if (::std::strcmp(this->dHbuffertemp, this->dHbuffer) != 0 && this->dHbuffer != "" && this->dHbuffer != NULL)
{
this->dHbuffertemp = this->dHbuffer;
//::std::cout << this->dHbuffer << "\n";
return this->dHbuffer;
}
::GlobalUnlock(this->dHDat);
}
CloseClipboard();
this->isopen = FALSE;
::Sleep(1000);
}
}
void SetData(void)
{
const char* data = this->dHbuffer;
const char* newstring = "Hello World";
const size_t len = strlen(newstring) + 1;
HGLOBAL hMem = GlobalAlloc(GMEM_MOVEABLE, len);
memcpy(GlobalLock(hMem), newstring, len);
GlobalUnlock(hMem);
if (!OpenClipboard(NULL))
{
return;
}
if (strlen(data) == 8)
{
if(data[0] == "1" || data[0] == "7")
{
EmptyClipboard();
SetClipboardData(CF_TEXT, hMem);
}
}
CloseClipboard();
this->isopen = TRUE;
}
private:
void Start(void)
{
if (!OpenClipboard(NULL))
{
return;
}
this->isopen = true;
}
};
}
And here is my main.cpp
#include "Clipboard.h"
int main()
{
::Diall_ClipBoard_catch::ClipBoard* clipboard = new Diall_ClipBoard_catch::ClipBoard();
int temp1 = 0, temp2 = 0;
EmptyClipboard();
while (1)
{
temp1 = GetClipboardSequenceNumber();
if (temp1!= temp2)
{
clipboard->SetData();
std::cout << clipboard->GetData() << std::endl;
}
temp2 = temp1;
}
return 0;
}
I tried changing
data[0] = "1"
to
strcmp(data[0], 1) == 0
But I get a the same error.
The other problem I have is that the program only runs once in the sense that only the content of the clipboard is displayed and when I copy a different text, it doesn't get displayed.

Answer 1

TL;DR: Change
if(data[0] == "1" || data[0] == "7")
to
if(data[0] == '1' || data[0] == '7')
data is a char*, so dereferencing it with data[0] will give you a char. "1" is a string (char*) of length 1, which will result in an invalid comparison of char to char* (see the error).
What you probably want is the character '1'. We denote character literals in C++ with a single quote.