/*主要是通过GetEnvironmentVariable实现的。其函数原型如下：DWORD GetEnvironmentVariable(		PCTSTR pszName, //记录要获取的参数名。		PTSTR pszValue,	//标记要获取的参数名对应的参数值		DWORD cchValue);//表示pszValue能容纳最大字符数。Note：如果cchValue为0，则函数返回值为pszName对应的参数值加上'\0'的字符数	一个正确获取参数值的用法如下：	*/void PrintEnvironmentVariable(PCTSTR pszVariableName){	PTSTR pszValue = NULL;	// Get the size of the buffer that is required to store the value	DWORD dwResult = GetEnvironmentVariable(pszVariableName, pszValue, 0);	if (dwResult != 0) 	{		// Allocate the buffer to store the environment variable value		DWORD size = dwResult * sizeof(TCHAR);		pszValue = (PTSTR)malloc(size);		GetEnvironmentVariable(pszVariableName, pszValue, size);		_tprintf(TEXT("%s=%s\n"), pszVariableName, pszValue);		free(pszValue);	}	else 	{		_tprintf(TEXT("'%s'=
    
     \n"), pszVariableName);	}}