custom ITOA not working right?

Question

I wanted to make a custom ITOA function to put large numbers into small strings, this is what I have coded :

main(){
    printf("itoa(2000000000,36)= '%s'",itoa(2000000000,36));
    printf("itoa(36,36)= '%s'",itoa(36,36));
    printf("itoa(37,36)= '%s'",itoa(37,36));

    return 1;
}

stock itoa(val, base)
{
    new buf[1024] = {0,...};
    new i = 1023;
    new LETTERZ[37] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',0};
    for(; val && i; --i, val /= base)
        buf[i] = LETTERZ[val % base];
    return buf[i+1];
}

It's based on 'C' code from this page: http://www.jb.man.ac.uk/~slowe/cpp/itoa.html

But somehow this is the output:

[20:34:35] itoa(2000000000,36)= 'X' [20:34:35] itoa(36,36)= '1' [20:34:35] itoa(37,36)= '1'

And this is totally wrong, I don't know which output to expect but 36 and 37 for sure can't be the same output and 2 000 000 000 can't be just 'X', as X is suposed to be 35, not 2 000 000 000, ZZ should be 1295 I think... I want to base this on the hexadecimal system, but with all the alfabet letters.

Could anyone tell me what's wrong here?

I'm working with a typeless language called PAWN (also known as SMALL) and later i want to use this code in VB.NET

Answer 1

THe solution seemed to be simple, the return buf[i+1] just returned one character so what I did is make it return an array:

new _s@T[4096];
#define sprintf(%1) (format(_s@T, SPRINTF_MAX_STRING, %1), _s@T)

main(){
    new num = atoi("ABCDEFG",36);
    printf("%d",num);
    printf("%s",itoa(num,36));

    return 1;
}

stock itoa(val, base)
{
    new buf[1024] = {0,...};
    new LETTERZ[37] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',0};
    for(new pos = 0; val;++pos,val = floatround(val/base,floatround_floor))
        strins(buf,sprintf("%c",LETTERZ[val % base]),0);
    return buf;
}

stock atoi(val[], base)
{
    new CURRNUM = 0;
    new len = strlen(val);
    new LETTERZ[37] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',0};
    for(new i = 0; i < len; ++i)
    {
        for(new x = 0; x < base; ++x)
        {
            new y = (len-i)-1;
            if(val[y] == LETTERZ[x])
            {
                CURRNUM += x*floatround(floatpower(base,i));
            }
        }
    }
    return CURRNUM;
}

Answer 2

/* itoa example */
#include <stdio.h>
#include <stdlib.h>

int main ()
{
  int i;
  char buffer [33];
  printf ("Enter a number: ");
  scanf ("%d",&i);
  itoa (i,buffer,10);
  printf ("decimal: %s\n",buffer);
  itoa (i,buffer,16);
  printf ("hexadecimal: %s\n",buffer);
  itoa (i,buffer,2);
  printf ("binary: %s\n",buffer);
  return 0;
}

You only give the number and the base, but parameter 2 needs a pointer to char already allocated. Use a buffer or try NULL, so the function will return the result.