Streams

Reading and Writing Text Files

You read in a single character with a get method.
```
char ch;
input_data.get(ch);
```

If you read a character and you regretted it, you can unget it, so that the next input operation can be read again.

char ch;
input_data.get(ch);
if ('0' <= ch && ch <= '9') /* it was a digit */
{
   input_data.unget(); /* oops - didn't want to read it */
   int n;
   input_data >> n; /* read integer starting with ch */
}

This is called one-character lookahead: at the next character in the input stream you can make a decision what you want to read in next, but not more than one character.
Older implementations of the stream library do not have the unget member function - use input_data.put_back(ch) instead.
When you are done using a file, you should close it.
```
input_data.close();
```

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