why getline ignoring first character of input while using in loop?

Question

do
{
 system("cls");
        cout<<"Enter Item Name:"<<endl;
        cin.ignore();
        cin.getline(item_name,size);
        cout<<item_name<<endl;
        cout<<"Enter Item Price:"<<endl;
        cin>>item_price;
cout<<" Do You Want To Add More Item..?\nPress Y/N."<<endl;
char c;
c=getche();
}while(c=='y'||c=='Y');

this is the pace of code , actually i am using this in my project, i cannot remove cin.ignore because i have to get input from user unless user press any other character rather then y

Answer 1

You know the answer to your question in the title. The call

cin.ignore();

reads the next character from cin and discards it.

The real question that you are grappling with, I think, is: how do you terminate the loop?

That's simple enough. Don't compare just one character. Compare the entire line.

do
{
   system("cls");
   cout << "Enter Item Name:"<<endl;
   cin.getline(item_name, size);
   cout << item_name << endl;
   cout << "Enter Item Price:" << endl;
   cin >> item_price;

   cout << "Do You Want To Add More Item..?\nPress Y/N." << endl;
   std::string ans;
   getline(cin, ans);

} while (ans == "y" || ans == "Y");

Answer 2

You can use following. Use cin.ignore(); after the line c=getche(); :

char c;
do
{
        system("cls");
        cout<<"Enter Item Name:"<<endl;
        cin.getline(item_name,size);
        cout<<item_name<<endl;
        cout<<"Enter Item Price:"<<endl;
        cin>>item_price;
        cout<<" Do You Want To Add More Item..?\nPress Y/N."<<endl;
        c=getche();
        cin.ignore();
}while(c=='y'||c=='Y');