C / C++ / MFC

  <pre>#include<iostream>
#include<conio.h>
#include<string.h>
#include<fstream>

using namespace std;
enum type{ home,work,fax,mobile,other };
struct contact{
	char num[15];
	char name[20];
	char TphoneN[6];
}phone[5];
const int max=5;
int index=0;

//reading function
bool reading(){
	char v;
	if(index<=5){
		cout<<"please enter phone number: ";
		gets(phone[index].num);
	
		cout<<"please enter the name: ";
		gets(phone[index].name);
	
		cout<<"the type of number( fax,  mobile,  home,  work,  other): ";
		gets(phone[index].TphoneN);
		/*cin>>v;
		switch(v){
			case 'f': phone[index].TphoneN='fax';
				break;
			case 'm': phone[index].TphoneN='mobile';
				break;
			case 'h': phone[index].TphoneN='home';
				break;
			case 'w': phone[index].TphoneN='work';
				break;
			case 'o': phone[index].TphoneN='other';
				break;
			default: cout<<"please enter a valid key: ";
		}*/
		index++;
		
		return true;
	}
	else 
		return false;
			
	}

//deleting function
bool delet(){
	int flag=0;
	cout<<"please enter the name of the person u wanna delete: ";
	char del[20];
	cin.getline(del,20);
	for(int i=0; i<=index; ++i){
		if(phone[i].name==del){
			for(int j=i; j<=index; ++j){
			
				phone[j].num=phone[j+1].num;
				phone[j].TphoneN=phone[j+1].TphoneN;
				phone[j].name=phone[j+1].name;
		 }
		 flag=1;
		}
}
	
	if(!flag){
		return false;
	}
	else{
			index--;
		return true;
	}
}

//function displqying all contacts
void all(){
	for(int i=0; i<=index; ++i){
		cout<<phone[i].name<<"\t"<<phone[i].num<<"\t"<<phone[i].TphoneN<<endl;
		cout<<"\n";
	}
}

//main function
int main(){
	int x;
	while(!0){
		cout<<"****"<<index<<"contact entries **** \n";
		cout<<"0 end \n1 new contact \n2 delete contact \n3 all contact \n4 empty contact memory";
		cin>>x;
		switch(x){
			case 1:
				bool y=reading();
				if(y==true){
					cout<<"contact successfuly saved";
				}
				else
					cout<<"an error accure could not save your contact";
			break;
			case 2:
			bool y=delet();
				if(y==true){
				cout<<"contact successfuly deleted";
			}
			else
				cout<<"sorry your name does not exist";
			break;
			case 3:
				all();
				break;
			case 4:
				cout<<"still searching";
				break;
			default:
				cout<<"sorry invalid key";
				break;
		}
	}
}

MyDlg::MyDlg(CWnd* pParent /=NULL/)
    : CDialogEx(IDD_DLG, pParent)
{
    m_Name = _T("");
    m_Status = _T("");
    m_Comments = _T("");
}

CHeaderCtrl* pHeader = (CHeaderCtrl*)m_ListControl.GetDlgItem(0);

void CMyDlg::ResetListControl() {
	m_ListControl.DeleteAllItems();
	int iNbrOfColumns;
	CHeaderCtrl* pHeader = (CHeaderCtrl*)m_ListControl.GetDlgItem(0);/* <---- this line */
	if (pHeader) {
		iNbrOfColumns = pHeader->GetItemCount();
	}
	for (int i = iNbrOfColumns; i >= 0; i--) {
		m_ListControl.DeleteColumn(i);
	}
}

m_Name

m_Name(_T(""))

BOOL CMyDlg::OnInitDialog()
{
	CDialogEx::OnInitDialog();
        ..........
        ..........
    return TRUE;
}

CDialogEx::OnInitDialog()

BOOL CMyDlg::OnInitDialog()

BOOL CWindowApp::InitInstance()
{
   CWinApp::InitInstance();/* <--- this line */

   CMyDlg dlg;
   m_pMainWnd = &dlg;
   INT_PTR nResponse = dlg.DoModal();
   .......
   .......
   .......
}

Quote:

Is this concept similar for CWinApp::InitInstance . Even when I commented this line my application still works. why?

1. The CWinApp::InitInstance does nothing, so it is safe to discard its call.
2. InitInstance does perform some initialization that now is missing in your application. Your application may run fine, at the moment, (for instance because it doesn't need such initializations) but this is definitely not a safe scenario.

Quote:

hy do we assign the address of the dialog to m_pMainWnd?

I know m_pMainWnd is a CWnd* m_pMainWnd.

Quote:

extern DWORD dwTlsIndex;
static DWORD dwTlsIndex;

DWORD dwTlsIndex;

• You don't need the extern declaration in the file that defines the variable.
• The static keyword makes the variable having file-scope (link failure).

#ifdef ZOS
...
#else
BOOL SYSREAD(...)
{
    return ReadFileEx(...);
}
#endif