sum char array

[xxxrugby]

I am traying to make program that takes from input strings s1 and s2 and then write them out in output string s3 in what are sum of numbers thar are write in s1 and s2.
for example: if is
s1='11111111'
s2='11112222' then program must sum s3 and like rezult have to get
s3='22223333'

for example: if is
s1 = '19'
s2 = '1001', then
s3 = '1020'.

But I have little trouble. Almost everything is doing just fine!
First here you are my code and after code I will put my results. And there you will see what is wrong!

#include <stdio.h>
#include <stdlib.h>

#define SIZE 1024

void zbroji( char*, char*, char*); 
               
int main()
{
    char s1[SIZE]; char s2[SIZE]; char s3[SIZE]; int i = 0;
    scanf("%s", s1);
    scanf("%s", s2);
    
    zbroji(s1, s2, s3);
    
    while( s3[i] != '\0')     /*Here need to be printf("%s", s3); but then is something wrong*/
    {
        printf("%d", s3[i]);
        i++;
    } 
    printf("\n");    
     system("PAUSE");
     return 0;
}

void zbroji(char a[SIZE], char b[SIZE], char c[SIZE])
{
    int i = 0, j = 0, k = 0, l = 0; int lena = 0, lenb = 0;
    int BIG = 0; int salji = 0; int SMALL = 0; char TEMP[SIZE]; int temp;
    
    while( a[lena] != '\0')
        lena++;
    while( b[lenb] != '\0')
        lenb++;
    lena -= 1; lenb -= 1;
    if( lena >= lenb)
    {
        BIG = lena;
        SMALL = lenb; 
    }
    else
    {
        BIG = lenb;
        SMALL = lena;
    }
    temp = BIG;
    c[BIG + 1] = '\0';
    for( i = BIG; i >= 0; i--, lena--, lenb--, BIG--)
    {
        if( lena < 0 )
        {
			j = 0;
        }
        else
        {
          if ( lenb < 0 )
		  {
		      k = 0;
		  }
          else
		  {
                j = a[lena] - '0'; k = b[lenb] -'0';
		  }
        }

        l = 0;       
        l = j + k + salji;
        if( l > 9)
        {
            if ( BIG == 0 )
                c[BIG] = l;
            else
            {
                c[BIG] = l - 10;
                salji = 1;
            }
        }
        else
        {
            c[BIG] = l;
        }
    }    
}

Output is:
s1 = 1111
s2 = 2222
s3 = 3333    that's OK!

s1 = 999
s2 = 999 
s3 = 1998 that's OK!

s1 = 11
s2 = 1111
s3 = 1122 that's OK! 

But when I make like this
s1 = 555
s2 = 5555
s3 = 611    WRONG!
or
s1 = 9999
s2 = 99
s3 = 10      WRONG!

[itsme86]

Your code is really hard to read, mostly because of your variable naming scheme but partly because of your odd indentation style. I think I'd do it more like this:

#include <stdio.h>
#include <string.h>

#define MAXLEN 4096

void get_number(char *name, char *buf)
{
  char *p;

  printf("%s number: ", name);
  fflush(stdout);
  fgets(buf, MAXLEN, stdin);
  if((p = strchr(buf, '\n')))
    *p = '\0';
}

void big_add(char *s1, char *s2, char *buf)
{
  char temp[MAXLEN];
  char *p, *q, *t;
  int num, carry = 0;

  p = s1 + strlen(s1) - 1;
  q = s2 + strlen(s2) - 1;
  t = temp;

  while(p >= s1 || q >= s2)
  {
    num = carry;
    num += p >= s1 ? *p - '0' : 0;
    num += q >= s2 ? *q - '0' : 0;

    if((carry = num / 10))
      num -= 10;

    *t++ = num + '0';
    p--;
    q--;
  }

  if(carry && t - temp < MAXLEN)
    *t = '1';
  else
    t--;

  while(t >= temp)
    *buf++ = *t--;
  *buf = '\0';
}

int main(void)
{
  char s1[MAXLEN], s2[MAXLEN], s3[MAXLEN];

  get_number("First", s1);
  get_number("Second", s2);

  big_add(s1, s2, s3);

  printf("Result: %s\n", s3);
  return 0;
}

itsme@dreams:~/C$ ./bigadd
First number: 555
Second number: 5555
Result: 6110
itsme@dreams:~/C$ ./bigadd
First number: 283749208374983274
Second number: 746391823749187234
Result: 1030141032124170508

If you don't understand something in it just let me know.

[xxxrugby]

Thanks!
I never seen this before

get_number("First", s1);

I will look at FAQ for this. I know is there somwhere

fflush(stdout);
  fgets(buf, MAXLEN, stdin);

I undersand else mostly!

[itsme86]

get_number("First", s1); just passes 2 strings to the get_number() function. I'm not sure what you don't understand about it.

fflush(stdout); needs to be called when you print a string that doesn't end with a newline. It's not necessary on all OS's, but some won't display the string until a newline is printed or the buffer is flushed.

fgets(buf, MAXLEN, stdin); is definitely in the FAQ. Look for the FAQ on getting input from the user.

[Krak]

I am traying to make program that takes from input strings s1 and s2 and then write them out in output string s3 in what are sum of numbers thar are write in s1 and s2.

for example: if is
s1 = '19'
s2 = '1001', then
s3 = '1020'.

They invented this cool data type a while ago....maybe you've heard of it....it's called INT. If you want to add numbers together...use a freaking int. See dear, that makes things a lot easier.

Instead of going through a bunch of tedious crap, you can use this great operator called '+'. It does wonders for adding numbers.

[itsme86]

They invented this cool data type a while ago....maybe you've heard of it....it's called INT. If you want to add numbers together...use a freaking int. See dear, that makes things a lot easier.

Instead of going through a bunch of tedious crap, you can use this great operator called '+'. It does wonders for adding numbers.

Try adding these 2 numbers using ints...

itsme@dreams:~/C$ ./bigadd
First number: 283749208374983274
Second number: 746391823749187234
Result: 1030141032124170508

[Krak]

An unsigned long int will give you as big of a number as you're ever going to need.

[laserlight]

An unsigned long int will give you as big of a number as you're ever going to need.

In some fields (e.g. branches of mathematics, applications of cryptography) numbers of arbitrary precision need to be represented for certain calculations.

[InvariantLoop]

isnt a unsigned long int = 4 bytes with values ranging from 0 - 4.294.967.295 ? how are they keeping track on the US national debt that is 7 trillion? silly question but im curious.

[MadCow257]

They could use an __int64.

how are they keeping track on the US national debt that is 7 trillion

EDIT
According to http://www.brillig.com/debt_clock/ the debt is actually closer to 8 trillion.
Scary
/EDIT

In some fields (e.g. branches of mathematics, applications of cryptography) numbers of arbitrary precision need to be represented for certain calculations.

Indeed, an algorithm like RSA uses 768+ bits often, although i've never seen it used with more then 2048 bits.

[Dave_Sinkula]

An unsigned long int will give you as big of a number as you're ever going to need.

"640K ought to be enough for anybody."

isnt a unsigned long int = 4 bytes with values ranging from 0 - 4.294.967.295 ?

That range is a minimum, the size is whatever it needs to be to contain that minimum -- one byte might suffice on some systems.