Subj : Re: directly inputting numbers
To   : borland.public.cpp.borlandcpp
From : "Michael Fruchter" <mfruchtr@yahoo.com>
Date : Thu Jul 17 2003 12:45 pm

How will the program know where the number ends? I'm dealing
with a text that has many numbers that are not delimited (e.g. by spaces) but are of fixed width. I was hoping that it's 
possible to specify the amount of characters that you want to
read into your integer (analogous to fgets with strings). 


maeder@glue.ch (Thomas Maeder [TeamB]) wrote:
>"Michael Fruchter" <mfruchtr@yahoo.com> writes:
>
>> Is there a way to directly input a number from a non-delimited text as
>> opposed to reading in a certain amount of characters using "fgets" and
>> converting to an integer using "atoi" (and then, if necessary, dividing
>> by 10^x for x decimal places)?
>
>You can use the Standard C++ iostream functionality, e.g.:
>
>#include <iostream>
>#include <istream>
>#include <ostream>
>
>int main()
>{
>  int i;
>  if (std::cin >> i)
>  {
>    ; // do something useful with i
>    return EXIT_SUCCESS;
>  }
>  else
>  {
>    std::cerr << "input failure\n";
>    return EXIT_FAILURE;
>  }
>}
>
>You can read values of other numerical types by simply substituting them for
>int. If you have the text in a string already, you can use a
>std::istringstream or a std::istrstream instead.
>
>
>[Note that what I wrote above is ISO Standard C++ syntax. Even the latest
>release of Borland C++ predates this standard by years. While the functionality
>is supported, you will probably have to adjust the syntax a bit to make
>Borland C++ accept this code.]

.