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From: ark@alice.UUCP
Newsgroups: comp.lang.c
Subject: Re: Big numbers in C?
Message-ID: <7139@alice.UUCP>
Date: Tue, 28-Jul-87 11:07:02 EDT
Article-I.D.: alice.7139
Posted: Tue Jul 28 11:07:02 1987
Date-Received: Fri, 31-Jul-87 02:10:35 EDT
References: <1192@killer.UUCP>
Organization: AT&T Bell Laboratories, Liberty Corner NJ
Lines: 37
Keywords: big numbers

In article <1192@killer.UUCP>, robertl@killer.UUCP writes:
> I was wondering....How do I use large numbers (over 32000) in C?  I know about
> float type, but that give it in wierd numbers.  I need numbers in the hundreds
> of millions, and I need them in real format. (i.e. 100000000), not float
> format.  If there a little script that could change float to real?

On most C implementations, the "long" type is stored as a 32-bit
signed integer.  That means you can store integer values between
-2147483648 and 2147483647, inclusive.  Is that big enough?

A quick example:

	long foo;
	foo = 123456789L;
	printf ("%ld\n", foo);

Notice the L at the end of the constant to say that it is a long
number, and the %ld format item to print it.

> Also, I am having a little trouble with this statement:
> 
> strtol(data.number);
> 
> Where:  data.number[1] == 5
>         data.number[2] == 7  /*Or whatever...Just examples*/
>         data.number[3] == \0

When using something like strtol, the elements of the array you
are converting should be representations of characters, not
small integers.  The following should work:

	data.number[0] = '5';
	data.number[1] = '7';
	data.number[2] = 0;		/* or '\0' but not '0' */

Also note that subscripts in C start from 0, not 1.