How to copy string to clipboard in C?

Read the MSDN documentation for the SetClipboardData function. It appears you are missing a few steps and releasing the memory prematurely. First of all, you must call OpenClipboard before you can use SetClipboardData. Secondly, the system takes ownership of the memory passed to the clipboard and it must be unlocked. Also, the memory must be movable, which requires the GMEM_MOVEABLE flag as used with GlobalAlloc (instead of LocalAlloc).

const char* output = "Test";const size_t len = strlen(output) + 1;HGLOBAL hMem =  GlobalAlloc(GMEM_MOVEABLE, len);memcpy(GlobalLock(hMem), output, len);GlobalUnlock(hMem);OpenClipboard(0);EmptyClipboard();SetClipboardData(CF_TEXT, hMem);CloseClipboard();

I wrote an open source command line tool to do this in Windows:

http://coffeeghost.net/2008/07/25/ccwdexe-copy-current-working-directory-command/

ccwd.exe copies the current working directory to the clipboard. It's handy when I'm several levels deep into a source repo and need to copy the path.

Here's the complete source:

#include "stdafx.h"#include "windows.h"#include "string.h"#include <direct.h>int main(){    LPWSTR cwdBuffer;    // Get the current working directory:    if( (cwdBuffer = _wgetcwd( NULL, 0 )) == NULL )        return 1;    DWORD len = wcslen(cwdBuffer);    HGLOBAL hdst;    LPWSTR dst;    // Allocate string for cwd    hdst = GlobalAlloc(GMEM_MOVEABLE | GMEM_DDESHARE, (len + 1) * sizeof(WCHAR));    dst = (LPWSTR)GlobalLock(hdst);    memcpy(dst, cwdBuffer, len * sizeof(WCHAR));    dst[len] = 0;    GlobalUnlock(hdst);    // Set clipboard data    if (!OpenClipboard(NULL)) return GetLastError();    EmptyClipboard();    if (!SetClipboardData(CF_UNICODETEXT, hdst)) return GetLastError();    CloseClipboard();    free(cwdBuffer);    return 0;}

Take a look at Microsoft's Documentation on using the clipboard. This requires that your using the WinAPI, but this shouldn't be a problem since your on Windows. Note that programming the Windows API is never simple unless you use a very high-level language.