Add 4 20 digit numbers in C

[thehobbit]

Hi,

Could anyone give ideas on how to add 4 20 digit numbers in ANSI C and
pass the result back to a calling program in COBOL? We were able to
add up to 15 digit numbers without any problems, but we started facing
issues once we go above 15 digits.

Thanks,
Venkat

[Jack Klein]

On Wed, 07 Nov 2007 20:43:47 -0800, thehobbit <ve**********@g mail.com>
wrote in comp.lang.c:

Hi,

Could anyone give ideas on how to add 4 20 digit numbers in ANSI C and
pass the result back to a calling program in COBOL? We were able to
add up to 15 digit numbers without any problems, but we started facing
issues once we go above 15 digits.

ANSI C, or ISO C, or just plain standard C, does not define linkage to
COBOL or any other language. So there is no way to do this in "ANSI
C".

On the other hand, you may have an issue with numeric precision in the
C implementation you are using, regardless of how you are getting the
values into the C program.

But you haven't provided nearly enough information. What types are
these numbers? Integers, floating point, what? What data type are
they defined as in C?

And you haven't told us what "problems" you think you are having.

How many digits does the C data type you are using have?

If this is an integer type, you can look at the type_MAX macro in
<limits.hto tell you what the range of values the type can handle
is.

If you are using one of the floating point types, look at type_DIG in
<float.h>.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://c-faq.com/
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.l earn.c-c++
http://www.club.cc.cmu.edu/~ajo/docs/FAQ-acllc.html

[thehobbit]

Thank you for the details jack... actually am a nincompoop in C...
more of a COBOL programmer... actually what we are trying to do is add
4 20 digit integers and return the sum back to the COBOL program. This
is because COBOL has a limitation of 18 digits. When we added 15 4
digit integer numbers we got the expected sum, however the moment we
started adding 16 4 digit integers then the sum was all wrong... the
code we kind of wrote is as follows; Please let us know if you have
any suggestions...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*
* Function to add 4 integers
*/

void ccadd(char *inp1,char *inp2,char *inp3,char *inp4,char *out)
{
long long int_inp1,int_in p2,int_inp3,int _inp4,int_out;
int_inp1 = atoi(inp1);
int_inp2 = atoi(inp2);
int_inp3 = atoi(inp3);
int_inp4 = atoi(inp4);

int_out = int_inp1 + int_inp2 + int_inp3 + int_inp4;
sprintf(out,"%l f",int_out);
}
On Nov 7, 9:20 pm, Jack Klein <jackkl...@spam cop.netwrote:

On Wed, 07 Nov 2007 20:43:47 -0800, thehobbit <venkat.na...@g mail.com>
wrote in comp.lang.c:

Hi,

Could anyone give ideas on how to add 4 20 digit numbers in ANSI C and
pass the result back to a calling program in COBOL? We were able to
add up to 15 digit numbers without any problems, but we started facing
issues once we go above 15 digits.

ANSI C, or ISO C, or just plain standard C, does not define linkage to
COBOL or any other language. So there is no way to do this in "ANSI
C".

On the other hand, you may have an issue with numeric precision in the
C implementation you are using, regardless of how you are getting the
values into the C program.

But you haven't provided nearly enough information. What types are
these numbers? Integers, floating point, what? What data type are
they defined as in C?

And you haven't told us what "problems" you think you are having.

How many digits does the C data type you are using have?

If this is an integer type, you can look at the type_MAX macro in
<limits.hto tell you what the range of values the type can handle
is.

If you are using one of the floating point types, look at type_DIG in
<float.h>.

--
Jack Klein
Home:http://JK-Technology.Com
FAQs for
comp.lang.chttp ://c-faq.com/
comp.lang.c++http://www.parashift.com/c++-faq-lite/
alt.comp.lang.l earn.c-c++http://www.club.cc.cmu.edu/~ajo/docs/FAQ-acllc.html

[Ian Collins]

thehobbit wrote:

In future, please don't top post.

Thank you for the details jack... actually am a nincompoop in C...
more of a COBOL programmer... actually what we are trying to do is add
4 20 digit integers and return the sum back to the COBOL program. This
is because COBOL has a limitation of 18 digits. When we added 15 4
digit integer numbers we got the expected sum, however the moment we
started adding 16 4 digit integers then the sum was all wrong... the
code we kind of wrote is as follows; Please let us know if you have
any suggestions...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*
* Function to add 4 integers
*/

void ccadd(char *inp1,char *inp2,char *inp3,char *inp4,char *out)

Make the inputs const char*.

{
long long int_inp1,int_in p2,int_inp3,int _inp4,int_out;
int_inp1 = atoi(inp1);

Don't use atoi to convert a C string to long long, use strtoll, or if
you are 100% sure the C strings represent valid numbers, atoll.

--
Ian Collins.

[thehobbit]

On Nov 7, 10:22 pm, Ian Collins <[e-mail] mwrote:

thehobbit wrote:

In future, please don't top post.

Thank you for the details jack... actually am a nincompoop in C...
more of a COBOL programmer... actually what we are trying to do is add
4 20 digit integers and return the sum back to the COBOL program. This
is because COBOL has a limitation of 18 digits. When we added 15 4
digit integer numbers we got the expected sum, however the moment we
started adding 16 4 digit integers then the sum was all wrong... the
code we kind of wrote is as follows; Please let us know if you have
any suggestions...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*
* Function to add 4 integers
*/

void ccadd(char *inp1,char *inp2,char *inp3,char *inp4,char *out)

Make the inputs const char*.

{
long long int_inp1,int_in p2,int_inp3,int _inp4,int_out;
int_inp1 = atoi(inp1);

Don't use atoi to convert a C string to long long, use strtoll, or if
you are 100% sure the C strings represent valid numbers, atoll.

--
Ian Collins.

thanks... i am sure that they represent valid numbers.. but not able
to use atoll function on my system (called HP3000)... gives a run time
error. any particular library needs to be included when using the
atoll function?

[Richard Heathfield]

thehobbit said:

On Nov 7, 10:22 pm, Ian Collins <[e-mail] mwrote:

<snip>

>>
Don't use atoi to convert a C string to long long, use strtoll, or if
you are 100% sure the C strings represent valid numbers, atoll.

thanks... i am sure that they represent valid numbers.. but not able
to use atoll function on my system (called HP3000)... gives a run time
error. any particular library needs to be included when using the
atoll function?

Ian was working on the incorrect assumption that you have access to a C99
compiler. It is odd that he should assume this, since practically nobody
has access to a C99 compiler.

The problem you are having is that the numbers you wish to add are too big
to fit into any of the integer types you appear to have available on your
system, and too big to fit *exactly* into any of the floating point types.

It's at times like this that you need to reach for your friendly
neighbourhood "bignum" library, such as GMP (Gnu Maths Package, I think)
or Miracl. These libraries provide the functionality you need. (If you
don't like that answer, you could do what I did, which is to write your
own bignum library - and, if all you want to do is add two (or more) big
numbers together, it's pretty easy to do that yourself. Just think about
how you stop overflow. In fact, just think about how you don't even
*consider* overflow when adding numbers with pencil and paper. It's never
an issue, is it? Why not? Because you have more paper on the left, that's
why, and you allocate enough for your needs, which you can more or less
work out in your head (for any two numbers neither of which is more than D
digits long, D + 1 digits will suffice to store the answer, sometimes with
room to spare).

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

[Ian Collins]

Richard Heathfield wrote:

thehobbit said:

>On Nov 7, 10:22 pm, Ian Collins <[e-mail] mwrote:

<snip>

>>Don't use atoi to convert a C string to long long, use strtoll, or if
you are 100% sure the C strings represent valid numbers, atoll.

thanks... i am sure that they represent valid numbers.. but not able
to use atoll function on my system (called HP3000)... gives a run time
error. any particular library needs to be included when using the
atoll function?

Ian was working on the incorrect assumption that you have access to a C99
compiler. It is odd that he should assume this, since practically nobody
has access to a C99 compiler.

It seamed a fair assumption as he was using long long. I don't know
about other platforms, but Solaris has had these function for at least a
decade. I'm sure most people here have access to systems with strtoll
and compilers with long long, fully C99 compliant or not.

--
Ian Collins.

[Richard Heathfield]

Ian Collins said:

Richard Heathfield wrote:

<snip>

>Ian was working on the incorrect assumption that you have access to a
C99 compiler. It is odd that he should assume this, since practically
nobody has access to a C99 compiler.

It seamed a fair assumption as he was using long long.

Ian, I apologise. I am guilty of not reading the thread history carefully
enough. He does indeed use long long int in his own code, and what was
needed was indeed a C99 usage lesson rather than a bignum package.

<snip>

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

[Nick Keighley]

don't top post. I've rearranged things
On 8 Nov, 06:13, thehobbit <venkat.na...@g mail.comwrote:

On Nov 7, 9:20 pm, Jack Klein <jackkl...@spam cop.netwrote:

On Wed, 07 Nov 2007 20:43:47 -0800, thehobbit <venkat.na...@g mail.com>

Could anyone give ideas on how to add 4 20 digit numbers in ANSI C and
pass the result back to a calling program in COBOL? We were able to
add up to 15 digit numbers without any problems, but we started facing
issues once we go above 15 digits.

ANSI C, or ISO C, or just plain standard C, does not define linkage to
COBOL or any other language. So there is no way to do this in "ANSI
C".

On the other hand, you may have an issue with numeric precision in the
C implementation you are using, regardless of how you are getting the
values into the C program.

But you haven't provided nearly enough information. What types are
these numbers? Integers, floating point, what? What data type are
they defined as in C?

And you haven't told us what "problems" you think you are having.

How many digits does the C data type you are using have?

If this is an integer type, you can look at the type_MAX macro in
<limits.hto tell you what the range of values the type can handle
is.

If you are using one of the floating point types, look at type_DIG in
<float.h>.

--
Jack Klein
Home:http://JK-Technology.Com
FAQs for
comp.lang.chttp ://c-faq.com/
comp.lang.c++http://www.parashift.com/c++-faq-lite/
alt.comp.lang.l earn.c-c++http://www.club.cc.cmu.edu/~ajo/docs/FAQ-acllc.html

don't quote sigs (the bit after ("-- ")

Thank you for the details jack... actually am a nincompoop in C...
more of a COBOL programmer... actually what we are trying to do is add
4 20 digit integers and return the sum back to the COBOL program. This
is because COBOL has a limitation of 18 digits. When we added 15 4
digit integer numbers we got the expected sum,

? confusion

if you want to add 4 20-digit numbers why are you adding 4-digit
numbers?

however the moment we
started adding 16 4 digit integers then the sum was all wrong...

could you give an example of the numbers you used that gave the wrong
answer?

the code we kind of wrote is as follows;

this code doesn't add 16 numbers

Please let us know if you have
any suggestions...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*
* Function to add 4 integers
*/

void ccadd(char *inp1,char *inp2,char *inp3,char *inp4,char *out)

this is more of a style point. Why not use an array? And since your
program doesn't change the input values make it const.

void ccadd (const char *inp[], int in_count, char *out)

{
long long int_inp1,int_in p2,int_inp3,int _inp4,int_out;
int_inp1 = atoi(inp1);

atoi() has poor error checking. And it doesn't return a long long.
Use a strtoX() function. And use one that returns a long long
or unsigned long long. Check for errors.

int_inp2 = atoi(inp2);
int_inp3 = atoi(inp3);
int_inp4 = atoi(inp4);

int_out = int_inp1 + int_inp2 + int_inp3 + int_inp4;
sprintf(out,"%l f",int_out);

}

try posting a complete program and its results
--
Nick Keighley

[Ben Bacarisse]

thehobbit <ve**********@g mail.comwrites:

On Nov 7, 10:22 pm, Ian Collins <[e-mail] mwrote:

>thehobbit wrote:

/*
* Function to add 4 integers
*/

void ccadd(char *inp1,char *inp2,char *inp3,char *inp4,char *out)

Make the inputs const char*.

{
long long int_inp1,int_in p2,int_inp3,int _inp4,int_out;
int_inp1 = atoi(inp1);

Don't use atoi to convert a C string to long long, use strtoll, or if
you are 100% sure the C strings represent valid numbers, atoll.

--
Ian Collins.

Please don't keep quoting sigs.

thanks... i am sure that they represent valid numbers.. but not able
to use atoll function on my system (called HP3000)... gives a run time
error. any particular library needs to be included when using the
atoll function?

I have not heard of atoll but some versions of HP-UX do seem to be
missing strtoll. It would appear they have strtoimax[1] which is a
POSIX function to do the same job. I say "seem" and "appear to"
because I don't know -- I just did the web search you should have done
when you found the answer was a function that seems to be missing --
strtoll.

[1] http://www.opengroup.org/onlinepubs/...strtoimax.html

--
Ben.