Are there other string classes?

**Daved** · 12-22-2008

There are several common issues with using cin and probably quite a few more that aren't common.

For example, if you don't need to handle bad input, then you can get away with always calling cin.ignore() after calls to cin >> to ignore the trailing newline.

If you do want to handle error conditions, then something like this usually works:

Code:

// prompt here

while (!(cin >> data) || cin.get() != '\n')
{
  cin.clear();
  cin.ignore(numeric_limits<streamsize>::max(), '\n');

  // error message and re-prompt here
}

Both those solutions allow mixing of cin >> and getline.

If you want it all encapsulated in some functions, see this post:

http://cboard.cprogramming.com/showp...4&postcount=24

**brewbuck** · 12-22-2008

I don't understand the griping about how hard it is to do a certain thing. Is reading a single line of input hard? Maybe for some people -- I don't really think so -- but whether it's hard or not, why not just get it right once, throw it in your personal library "bag of tricks" and forget about it.

Sure, sometimes stuff is "hard." So write the code and then never write it again.

**matsp** · 12-22-2008

Originally Posted by brewbuck

Sure, sometimes stuff is "hard." So write the code and then never write it again.

I agree, except that once you've gained another year or five of experience, you can usually come up with a better way to solve the same problem.

--
Mats

**Elysia** · 12-23-2008

Perhaps it is more of a lot of code to do such an easy and common thing. Having to repeat all that code can be tiring. There is "standard" solution available out of the box.

**whiteflags** · 12-23-2008

Originally Posted by Elysia

Code:

std::cin >> type;

My input class performs this beautifully without the need to worry for cleaning the input.
So if that sort of thing is what you need, I may have the solution wrapped inside a class, which I posted some time ago.

So does cin evidently.

I thought we all agreed that class you made suffered from feature creep and the better solution was a collection of free functions.

**Elysia** · 12-23-2008

No, you rejected the newer features, which I took under advisement, but not the latest working version I posted.

**C_ntua** · 12-23-2008

So where can this function be found?

**Elysia** · 12-23-2008

It is a class I had made and I wish I knew. I do not have its address an I cannot search for it.

**C_ntua** · 12-23-2008

Well, if you want to read user input, until an enter is pressed, and just not want to worry about something going bad, then you can use something like this. Note that this isn't to use exactly how it is, it is just a quick possibly non-working example

Code:

bool getlineSafe (istream& is, string& str)
{
        try 
        {
              getline(is, str);
              return true;
        }
        catch()
        {
              return false;
        }
}

If an error occurs you can handle it as you want. Or you can use another method rather than try/catch. The point is that if an error occurs you will need to handle it or ignore it. You don't really have another option.

Personally I use the simplest function, like get() to get one by one characters and do exactly what I want. Wrap it in a class/function with some parameters and not worry about it again

**Elysia** · 12-23-2008

I do not know if an empty catch works, though. Does it?

**laserlight** · 12-23-2008

Originally Posted by C_ntua

Well, if you want to read user input, until an enter is pressed, and just not want to worry about something going bad, then you can use something like this.

That is not very useful though. By default, std::getline() would not throw an exception due to an I/O error. One might as well just use the return value of std::getline() since it is indirectly convertible to bool.

Originally Posted by Elysia

I do not know if an empty catch works, though. Does it?

I believe it is a syntax error, but that was just an example anyway.

**finnepower** · 12-27-2008

The number of replies confirm the complexity of this. And impatient as i am, I'm moving to Python instead. I never need the low level benefits of C++ anyway.

**laserlight** · 12-27-2008

Originally Posted by finnepower

The number of replies confirm the complexity of this.

That is a rather naive measure: some of the replies are merely comments that the process is easier than what some people make it out to be.

Originally Posted by finnepower

And impatient as i am, I'm moving to Python instead. I never need the low level benefits of C++ anyway.

On the other hand, if you can get away with using a higher level language like Python (e.g., your program is I/O intensive rather than CPU intensive), it is usually a good idea to use that instead.

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