c++修改系统环境变量 （修改注册表以后，立刻使用SendMessageTimeout(HWND_BROADCAST进行广播）

#include "stdafx.h"
#include "addPath.h"

#define _AFXDLL
#include <afxwin.h>
#include <iostream>
#include <tchar.h>  
#include <afx.h>
#include <afxpriv.h>
using namespace std ;

int AddPath(char * strPath)
{
    HKEY hkResult;//键的句柄
    LPCTSTR environmentKey =_T("SYSTEM\\CurrentControlSet\\Control\\Session Manager\\Environment");
    //HKEY_CURRENT_USER   HKEY_LOCAL_MACHINE
    //LPCTSTR environmentKey =_T("Environment");
    if(ERROR_SUCCESS != RegOpenKeyEx(HKEY_LOCAL_MACHINE, environmentKey , 0,KEY_SET_VALUE | KEY_READ , &hkResult)) //打开键environment     
    {         
        MessageBox(NULL,_T("访问注册表出错！\n请使用管理员帐户执行本程序！"),_T("ERROR"),MB_ICONERROR); 
        return 0;
    }           
    DWORD BufferSize = 8192;   //数据长度   
    DWORD cbData;    ////数据长度   
    DWORD dwRet;        
    VOID* PerfData = malloc( BufferSize );//数据存放地址     
    cbData = BufferSize;        
      
    LPCTSTR myVariable=_T("PATH");//环境变量    
    dwRet = RegQueryValueEx( hkResult,myVariable, NULL, NULL, (LPBYTE) PerfData, &cbData ); //读取某子键下特定名称的值       
    while (dwRet == ERROR_MORE_DATA)    
    {         
        BufferSize += 4096;          
        PerfData = realloc( PerfData, BufferSize );          
        cbData = BufferSize;                
        dwRet = RegQueryValueEx( hkResult,myVariable,NULL,NULL,(LPBYTE) PerfData, &cbData );      
    }       
    //MessageBox(NULL,(LPCTSTR)PerfData,_T("我的系统变量Path"),MB_OK);
    
    if (dwRet == ERROR_SUCCESS)//名称不存在时，添加这个名称并设定其值    
    {   
        //判断是否存在myValue  
        if(IsPathExist(PerfData,strPath))  
        {  
            //MessageBox(NULL,_T("环境变量已经存在！"),_T("信息"),MB_OK);
            RegCloseKey(hkResult);//释放键句柄 
            free(PerfData);
            return 1;  
        }

        LPTSTR myValueEx = new TCHAR[strlen(strPath)+1];//此处，不是用sizeof() 函数，注意区别  
        strcpy((char*)myValueEx,strPath);  
        TCHAR lastChar=((LPTSTR)PerfData)[cbData-2];//字符串以\0结尾  
        if(lastChar!=';')  
        {  
            strcpy((char*)myValueEx,";");
            strcat((char*)myValueEx,strPath);   
            //printf("%s %s\n",strPath,myValueEx);  
            //printf("%d %d\n",strlen(strPath),strlen((char*)myValueEx)); 
        }      
    
        CString strMyValueEx;
        USES_CONVERSION;
        strMyValueEx = A2T((LPCSTR)myValueEx);
        //MessageBox(NULL,strMyValueEx,_T("信息"),MB_OK);
  
        TCHAR * temp = new TCHAR[cbData+strlen((char*)myValueEx)];  
        _tcscpy_s(temp, cbData, (LPTSTR)PerfData);//拷贝path中原有的字符串到temp中   
        //printf("temp:%s\n\n",temp);  
  
        LPTSTR pathValue = _tcscat(temp, strMyValueEx);  //类似memcpy           
        //printf("pathValue:%s\n\n",pathValue);  
  
        long setResult = RegSetValueEx(hkResult,myVariable,0, /*REG_SZ*/REG_EXPAND_SZ, (LPBYTE) pathValue,_tcsclen(pathValue)*sizeof(TCHAR));//设置某子键下特定名称的值。  
        DWORD dwResult;       
        SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE , 0,LPARAM(_T("Environment")), SMTO_ABORTIFHUNG, 5000, &dwResult);//广播立即执行  
        /*if(ERROR_SUCCESS == setResult)    
        {
            MessageBox(NULL,_T("环境变量设置完成！"),_T("信息"),MB_OK); 
        }
        else
        {
            MessageBox(NULL,_T("环境变量设置失败！"),_T("信息"),MB_OK); 
        }*/
        delete []myValueEx;
        delete []temp;  
        temp = NULL ;
    }  
    else  
    {  
        MessageBox(NULL,_T("环境变量读取失败！"),_T("信息"),MB_OK);
    }
    //printf("\nEnd Register\n");
    RegCloseKey(hkResult);//释放键句柄 
    free(PerfData);
    PerfData = NULL ;
    //printf("\nEnd AddPath\n");
    return 1;  
}

int IsPathExist(void *PerfData,char *myPath)
{
    //return 0 ;
    char * myoldPath = (char*)PerfData;
    int i = 0 ;
    while(myoldPath[i] != '\0')
    {
        i = i + 2 ;
    }
    char * path_t = new char[i/2+2];

    i = 0 ;
    while(myoldPath[i] != '\0')
    {
        path_t[i/2] = myoldPath[i];
        i = i + 2 ;
    }
    path_t[i/2] = '\0';
    path_t[i/2+1] = '\0';

    CString strMyoldPath;
    CString strMyPath;
    USES_CONVERSION;
    strMyoldPath = A2T((LPCSTR)path_t);
    strMyPath = A2T((LPCSTR)myPath);

    if(strMyoldPath[strMyoldPath.GetLength()-1] != ';')
    {
        strMyoldPath = strMyoldPath + _T(";") ;
    }
    if(strMyPath[strMyPath.GetLength()-1] != ';')
    {
        strMyPath = strMyPath + _T(";") ;
    }


    if(-1 == strMyoldPath.Find(strMyPath,0))
    {
        delete path_t;
        return 0 ;
    }

    delete path_t;
    return 1 ;
}

http://download.csdn.net/download/autumoonchina/8747921