MFC on the conversion and display of long string unsigned char and CString

Today I met about MD5 Generate registration code input and display problems , The solution process is recorded below

1、 Dialog window input CString turn unsigned char Array

	CString regstr;
	unsigned char reg_code[20]="1234";// Test array 
	unsigned char reg_code_md5[20];
	union TRAN_DATA 
	{
     
		char c_data;
		unsigned char uc_data;
	};
	TRAN_DATA tran_data;
	
	GetDlgItemText(IDC_EDIT_writereg,regstr);// Dialog input 
	DWORD dwNum = WideCharToMultiByte(CP_OEMCP,NULL,regstr.GetBuffer(),-1,NULL,0,NULL,FALSE);

	char *c_user_data = new char[dwNum];
	unsigned char *uc_user_data = new unsigned char[dwNum];
	memset( c_user_data,0 ,dwNum);

	WideCharToMultiByte (CP_OEMCP,NULL,regstr.GetBuffer(),-1,c_user_data,dwNum,NULL,FALSE);

	for(int i=0;i<dwNum;i++)
	{
    
		tran_data.c_data=c_user_data[i];
		uc_user_data[i]=tran_data.uc_data;
	}
	Write_Regcode(card_no[0],uc_user_data,reg_code_md5);
	//Write_Regcode(card_no[0],reg_code,reg_code_md5);// Test whether direct input is the same as dialog input 
		
	delete[] c_user_data;
	delete[] uc_user_data;
	c_user_data=NULL;
	uc_user_data=NULL;

2、 The dialog window displays MD5 code ,unsigned char Array rotation CString, The dialog box shows the output

	CString str;   
	CString str0;  
// for ( int i = 0; i < sizeof (reg_code_md5) / sizeof (reg_code_md5[0]); i++)
	for  ( int  i = 0; i <  16; i++)
	{
    
		str0.Format(_T("%02X"),reg_code_md5[i]);
		str +=str0;
	}
	SetDlgItemText(IDC_EDIT_readreg,str);

3、 test （MD5 Registration code after adding salt ）