Delete entries in Phone database

DocShoe

Please edit your posts and fix code formatting.
Split your code into several functions which perform one specific task.
You can use std::regex and std::regex_search to find partial matches
Use std::vector::erase() instead of rearranging elements yourself.
Get rid of index. std::vector offers a size() function which returns the number of elements the vector contains
Take advantage of iterators. Get rid of index variables at all.

codinglover2022

@DocShoe Ok here is the code. How can I use regex for partial match?

"```"
void ContactDelete(vector<Address>& list)
{
int entrynum, tmp = 0, index = 0;
charresponse;
system("cls");
cout << "\nProvide details of the Entry Number to Delete: ";
cin >> entrynum;

tmp = entrynum - 1;

if (entrynum > index)
{
cout << "There are only " << index << " entries in the book";
ContactDelete(list);
}
else
{
cin.clear();
cin.ignore();
cout << "\n[" << tmp + 1 << "]";
cout << setw(15) << list[tmp].fname;
cout << setw(15) << list[tmp].lname;
cout << setw(30) << list[tmp].addr;
cout << setw(15) << list[tmp].phone;
cout << endl << endl;
cout << "Delete Selected Entry? [Y]/[N]";
cin >> response;
if (response == 'y' || response == 'Y')
{
for (int i = tmp; i < (index - 1); i++)
{
list[i].fname = list[i + 1].fname;
list[i].lname = list[i + 1].lname;
list[i].addr = list[i + 1].addr;
list[i].phone = list[i + 1].phone;
}
--index;
ofstream fout;
fout.open("C:/Users/Delise/Documents//sample.txt");
for (int i = 0; i < index; i++)
{
fout << list[i].fname << "," << list[i].lname << "," << list[i].addr << "," << list[i].phone << ",";
}
fout.close();
cout << "\nSuccess Delete Entry!" << endl;
cout << endl << endl;
}
else if (response == 'n' || response == 'N')
cout << "Entry Deletion cancelled..." << endl;
}
cout << "Go to Main menu? [y]/[N]" << endl;
cin >> response;
if (response == 'y' || response == 'Y')
return;
else if (response == 'n' || response == 'N')
{
ContactDelete(list);
}
system("PAUSE");
}

"```"

DocShoe

If you don´t put effort in formatting your code properly, why do you think I would put effort in providing a solution/hint?

codinglover2022

@DocShoe Please find formatted code here.
Kindly review it.

"```"
void ContactDelete(vector<Address>& list)
{
int entrynum, tmp = 0, index = 0;
charresponse;
system("cls");
cout << "\nProvide details of the Entry Number to Delete: ";
cin >> entrynum;

tmp = entrynum - 1;

if (entrynum > index)
{
	cout << "There are only " << index << " entries in the book";
	ContactDelete(list);
}
else
{
	cin.clear();
	cin.ignore();
	cout << "\n[" << tmp + 1 << "]";
	cout << setw(15) << list[tmp].fname;
	cout << setw(15) << list[tmp].lname;
	cout << setw(30) << list[tmp].addr;
	cout << setw(15) << list[tmp].phone;
	cout << endl << endl;
	cout << "Delete Selected Entry? [Y]/[N]";
	cin >> response;
	if (response == 'y' || response == 'Y')
	{
		for (int i = tmp; i < (index - 1); i++)
	{
		list[i].fname = list[i + 1].fname;
		list[i].lname = list[i + 1].lname;
		list[i].addr = list[i + 1].addr;
		list[i].phone = list[i + 1].phone;
	}
	--index;
	ofstream fout;
	fout.open		("C:/Users/Delise/Documents//sample.txt");
	for (int i = 0; i < index; i++)
	{
		fout << list[i].fname << "," << list[i].lname << "," << list[i].addr << "," << list[i].phone << ",";
	}
	fout.close();
	cout << "\nSuccess Delete Entry!" << endl;
	cout << endl << endl;
}
else if (response == 'n' || response == 'N')
	cout << "Entry Deletion cancelled..." << endl;

}
cout << "Go to Main menu? [y]/[N]" << endl;
cin >> response;
if (response == 'y' || response == 'Y')
return;
else if (response == 'n' || response == 'N')
{
ContactDelete(list);
}
system("PAUSE");
}

"```"

codinglover2022

Updated code

void ContactDelete(vector<Address>& list)
{
	int entrynum, tmp = 0, index = 0;
	charresponse;
	system("cls");
	cout << "\nProvide details of the Entry Number to Delete: ";
	cin >> entrynum;

	tmp = entrynum - 1;

	if (entrynum > index)
	{
		cout << "There are only " << index << " entries in the book";
		ContactDelete(list);
	}
	else
	{
		cin.clear();
		cin.ignore();
		cout << "\n[" << tmp + 1 << "]";
		cout << setw(15) << list[tmp].fname;
		cout << setw(15) << list[tmp].lname;
		cout << setw(30) << list[tmp].addr;
		cout << setw(15) << list[tmp].phone;
		cout << endl << endl;
		cout << "Delete Selected Entry? [Y]/[N]";
		cin >> response;
		if (response == 'y' || response == 'Y')
		{
			for (int i = tmp; i < (index - 1); i++)
		{
			list[i].fname = list[i + 1].fname;
			list[i].lname = list[i + 1].lname;
			list[i].addr = list[i + 1].addr;
			list[i].phone = list[i + 1].phone;
		}
		--index;
		ofstream fout;
		fout.open		("C:/Users/Delise/Documents//sample.txt");
		for (int i = 0; i < index; i++)
		{
			fout << list[i].fname << "," << list[i].lname << "," << list[i].addr << "," << list[i].phone << ",";
		}
		fout.close();
		cout << "\nSuccess Delete Entry!" << endl;
		cout << endl << endl;
	}
	else if (response == 'n' || response == 'N')
		cout << "Entry Deletion cancelled..." << endl;
}
cout << "Go to Main menu? [y]/[N]" << endl;
cin >> response;
if (response == 'y' || response == 'Y')
	return;
else if (response == 'n' || response == 'N')
{
	ContactDelete(list);
}
system("PAUSE"); 
}

wob

Your functions are doing too much. Let's look at "ContactDelete". What does it do?

a) Ask user for input
b) print an Address object
c) move objects from a position to previous position (in a loop)
d) write to a file
e) call itself
f) all of a) to e)

The answer is f, obviously. This is way more than what a "ContactDelete" function should be doing. It should only do c). But you don't even need to implement c) yourself. See https://en.cppreference.com/w/cpp/container/vector/erase

So the most important lesson is: split your code into simple short functions which only do one thing.

As for your question about finding substrings in strings: there is string::contains from C++23, if you have an older version (likely), you can use string::find instead:
if (fullname.find(substring) != std::string::npos) { /* found */ } else { /* not found */ }

codinglover2022

Are you saying you could easily remove the name using the vector::erase along with std::remove?

Something like this as below.
#include <algorithm>
//...
name.erase(std::remove(name.begin(), name.end(), delete_contact), name.end());

DocShoe

@codinglover2022

Not quite, but close enough. There´s the erase-remove idiom. The idea is to provide some kind of criterion to identify the elements you want to remove from the vector. This is usually achieved by calling std::remove_if along with a lambda:

void some_func( std::vector<address>& addresses )
{
   // Lambda identifying the elements to be removed
   auto predicate = []( address const& addr )
   {
      // return true to remove the given addr, false otherwise
   };
   addresses.erase( std::remove_if( addresses.begin(), addresses.end(), predicate ),
                                    addresses.end() );                    
   }
}

Edit:
The erase-remove idiom is used when you want to remove multiple elements from the vector. If you want to remove only one item you can use a similar approach that removes the first element found:

void some_func( std::vector<address>& addresses )
{
   // Lambda identifying the elements to be removed
   auto predicate = []( address const& addr )
   {
      // return true to remove the given addr, false otherwise
   };
   auto it  = std::find_if( addresses.begin(), addresses.end(), predicate );
   if( it != addresses.end() )
   {
      addresses.erase( it ),
   }
}

wob

@codinglover2022 sagte in Delete entries in Phone database:

Are you saying you could easily remove the name using the vector::erase along with std::remove?

Something like this as below.
#include <algorithm>
//...
name.erase(std::remove(name.begin(), name.end(), delete_contact), name.end());

You are asking the user for the entry number to delete.

Therefore simply: addresses.erase(addresses.begin() + i).
No need for erase-remove.

Also: Not sure why you are now naming your vector of Address name. An address vector is not a name. The most generic name is addresses: plural because it is a vector. And address because the objects are of type Address.

codinglover2022

Below is the modified code , based on your inputs. Please review it.

void ContactDelete(vector<Address>& list)
{       
       	int tmp = 0, index = 0;
        char response;	
        auto predicate = [] (Address const& addr)
        {
        
        };
        auto it = std::find_if(list.begin(), list.end(), predicate);
        if(it != list.end())
        {
            list.erase(it),
        }

        	cout << setw(15) << list[tmp].fname;
		cout << setw(15) << list[tmp].lname;
		cout << setw(30) << list[tmp].addr;
		cout << setw(15) << list[tmp].phone;
		cout << endl << endl;
		cout << "Delete Selected Entry? [Y]/[N]";
		cin >> response;
		if (response == 'y' || response == 'Y')
		{
			for (int i = tmp; i < (index - 1); i++)
		{
			list[i].fname = list[i + 1].fname;
			list[i].lname = list[i + 1].lname;
			list[i].addr = list[i + 1].addr;
			list[i].phone = list[i + 1].phone;
		}
		ofstream fout;
		fout.open		("C:/Users/Delise/Documents//sample.txt");
		for (int i = 0; i < index; i++)
		{
			fout << list[i].fname << "," << list[i].lname << "," << list[i].addr << "," << list[i].phone << ",";
		}
		fout.close();
		cout << "\nSuccess Delete Entry!" << endl;
		cout << endl << endl;
	}
	else if (response == 'n' || response == 'N')
		cout << "Entry Deletion cancelled..." << endl;
}
cout << "Go to Main menu? [y]/[N]" << endl;
cin >> response;
if (response == 'y' || response == 'Y')
	return;
else if (response == 'n' || response == 'N')
{
	ContactDelete(list);
}
system("PAUSE"); 
}

DocShoe

F mark

You just copied a meaningless code snippet at the beginning of the function and did not change the rest. Even your lambda does not return a value.