goto 语句与递归

Question

I am writing a function that opens a file, where open mode depends upon user choice. Given below is the function

void open_file(char T)
{
    string name;
open:
    cout << "\n Enter filename/path : ";
    cin >> name;
    if(T == 'N')
        file.open(name);
    else 
        if(T == 'O')
        {
            file.open(name, ios::app | ios::in);
            if(!file)
            {
                cout << "\n File not found. Try again";
                goto open;
            }
            file.seekg(0);
        }
}

if the file is not found, the program goes to open: , for that I have used the unappreciated goto statement. Please note that open: starts after the declaration of name .

I want to know if goto open is less memory efficient / slower than open_file('O') or not, since open_file('O') will declare name every time it is called. Please note: The only reason people give for not using goto statements is that they make the program more complex.

Answer 1

It would be easier to read if you would have used a while block instead of goto . No need for recursion.

void open_file(char T)
{
    string name;
    bool retry;
    do {    
        retry = false;
        cout << "\n Enter filename/path : ";
        cin >> name;
        if(T == 'N')
            file.open(name);
        else 
            if(T == 'O')
            {
                file.open(name, ios::app | ios::in);
                if(!file)
                {
                    cout << "\n File not found. Try again";
                    retry = true;
                } 
                else
                    file.seekg(0);
            }
    } while (retry);
}