help in transforming into a general case..

i wrote this working code which transforms a string of one number into integer using recursion

Code:

---



#include <stdio.h>
 int one_num(char buf[],int index,int start);
int rid(char buf[],int index,int x);
int main()
{
        int res;
    char buf[] ="-000123                ";
        res=one_num(buf,0,0);
    printf("%d",res);
return 0;
}
int one_num(char buf[],int index,int start)
{
int y=1,x = 0;
 
        if(buf[start]=='-')
    {
        y=-1;
                index++;
      }
        if(buf[start]=='+')
    {
        index++;
      }
        x=rid(buf,index,0)*y;
return x;

}

int rid(char buf[],int index,int x)
{
if ((buf[index]<'0')||(buf[index]>'9'))
{
return x;
}
  x *= 10;
  x += buf[index]-'0';
 
return rid(buf,index+1,x);

}

---

i want to make a program which transforms number like "-123 56 8 "
into numbers of an array
i wrote a code wich should find the next number and transforms it.
but its not working
rid_next should return the index of the next number
but its not working

Code:

---

#include <stdio.h>
int rid_next(char buf[],int index,int x);
void spin(char buf[],int arr[],int index,int num);
int one_num(char buf[],int index,int start);
int rid(char buf[],int index,int x);
int main()
{
       
        int arr[2];
    char buf[] ="-000123                143                ";

        spin(buf,arr,0,0);
        printf("%d %d\n",arr[0],arr[1]);
return 0;
}
void spin(char buf[],int arr[],int index,int num)
{

        int loc;
   
        if (index=='\0')
        {
      return;
        }
        arr[num]=one_num(buf,index, index);
        loc=rid_next( buf,index,0);
       
    spin(buf,arr,loc,num+1);
}

int one_num(char buf[],int index,int start)
{
int y=1,x = 0;
 
        if(buf[start]=='-')
    {
        y=-1;
                index++;
      }
        if(buf[start]=='+')
    {
        index++;
      }
        x=rid(buf,index,0)*y;
return x;

}

int rid(char buf[],int index,int x)
{
if ((buf[index]<'0')||(buf[index]>'9'))
{
return x;
}
  x *= 10;
  x += buf[index]-'0';
 
return rid(buf,index+1,x);

}

int rid_next(char buf[],int index,int x)
{
    if ((buf[index]<'0')||(buf[index]>'9'))
{
    return index;
}
 
    return rid(buf,index+1,x);

}

---

??

i added another function nex_num which comes after rid_next
which i think i should point to the next number
but its not working
??

Code:

---

#include <stdio.h>
int nex_num(char buf[],int index);
int rid_next(char buf[],int index,int x);
void spin(char buf[],int arr[],int index,int num);
int one_num(char buf[],int index,int start);
int rid(char buf[],int index,int x);
int main()
{
       
        int arr[2];
    char buf[] ="-000123                143                ";

        spin(buf,arr,0,0);
        printf("%d %d\n",arr[0],arr[1]);
return 0;
}
void spin(char buf[],int arr[],int index,int num)
{

        int loc;
   
        if (index=='\0')
        {
      return;
        }
        arr[num]=one_num(buf,index, index);
        loc=rid_next( buf,index,0);
        loc=nex_num(buf,loc);
    spin(buf,arr,loc,num+1);
}

int one_num(char buf[],int index,int start)
{
int y=1,x = 0;
 
        if(buf[start]=='-')
    {
        y=-1;
                index++;
      }
        if(buf[start]=='+')
    {
        index++;
      }
        x=rid(buf,index,0)*y;
return x;

}

int rid(char buf[],int index,int x)
{
if ((buf[index]<'0')||(buf[index]>'9'))
{
return x;
}
  x *= 10;
  x += buf[index]-'0';
 
return rid(buf,index+1,x);

}

int nex_num(char buf[],int index)
{
  if ((buf[index]>='0')&&(buf[index]<='9'))
  {
      return index;
    }
 
return nex_num(buf,index+1);

}
int rid_next(char buf[],int index,int x)
{
    if ((buf[index]<'0')||(buf[index]>'9'))
    {
        return index;
    }
 
    return rid(buf,index+1,x);

}

---

you probably meant rid_next instead of rid... but what's the purpose of x? I would attempt something like:

Code:

---

int rid_next(char buf[],int size,int index) {
  if(index>size) return some_special_failure_value; // ?
  if(isdigit(buf[index])) return index; // !isdigit(buf[index]) is better
  return rid_next(buf,++index);
}

---

Is it still in your specifications to make it recursive?

Quote:

---

i added another function nex_num which comes after rid_next
which i think i should point to the next number
but its not working

---

so what? you stack bugs to make things more complicated to fix? focus on one problem, solve it and resume with what's left, besides your code is not an example of clarity. You should not 'think' a function does something, be sure it does. Test it.

yes only recurtion are allowed
my function are working in the base case.
x in that function is useless.
i called thos function
so the first will get me to the first char after the number
and the next one should go till it reaches the start of the number
but i cant see why its not working??

right, I misread your code.

your rid_next() doesn't work because you want it to return the index following the first token read, and to do that you use rid() which does the job but returns the converted value (token to integer), and not an index, so you simply can't use rid() in rid_next(). Either you recode rid_next() as rid() but returning an index or you modify rid() to keep a track of the last index used.

thats exactly what i have written here
correct?

Code:

---

int nex_num(char buf[],int index)
{
  if ((buf[index]>='0')&&(buf[index]<='9'))
  {
      return index;
    }
 
return nex_num(buf,index+1);
}

---

Yep, i misunderstood your code, this is fixed in my previous post.

I have been thinking, transgalactic2, that your solutions to your prof's specifications are becoming as sadistic as the specs themselves :rolleyes:

Anyway, here's an example of what I meant by using a getchar() based function to process your input. I obeyed all the rules you have given us so far, I think. The function will give you an array of strings, each one containing only numbers, and null terminated. That means you don't have to parse any spaces out!

Code:

---

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

int getintray (char **string, int len, int count, const int size) {
        int ch=getchar();
        if (ch==' ') {
                if ((len>0) && (count==size-1)) return len;
                if (len>0) string[count++][len]='\0';
                return getintray(string,0,count,size);
        } else if (ch=='\n') {
                if ((len>0) && (count==size-1)) return len;
                else {       
                        printf("More numbers please: ");
                        if (len>0) string[count++][len]='\0';
                        return getintray(string,0,count,size);
                }
        } else if ((ch>=48) && (ch<=57)) {
                if (len==0) string[count]=malloc(256);
                string[count][len++]=ch;
                return getintray(string,len,count,size);
        }
        else return getintray(string,len,count,size);
}
       

int main() {
        int len, i;
        char *string[4];
        printf("Enter 4 numbers seperated by spaces: ");
        len=getintray(string,0,0,4);
        for (i=0; i<4; i++) {        /* a loop for the demo */
                printf("%d: \"%s\"\n",i,string[i]);
                free(string[i]);  /* remember, malloc was used! */
        }
        return 0;
}

---

It ignores garbage and won't give up, eg:

Code:

---

Enter 4 numbers seperated by spaces: 45
More numbers please: 13
More numbers please: 44 98
0: "45"
1: "13"
2: "44"
3: "98"
[root~/C] ./a.out
Enter 4 numbers seperated by spaces: sdfgsa 33    56ads 17         
More numbers please: 4
0: "33"
1: "56"
2: "17"
3: "4"
[root~/C] ./a.out
Enter 4 numbers seperated by spaces:    1    2  124351234621  4 
0: "1"
1: "2"
2: "124351234621"
3: "4"
Enter 4 numbers seperated by spaces: 4123 89239 6279 27
0: "4123"
1: "89239"
2: "6279"
3: "27"

---

It doesn't process signs (+/-) -- for that you will have to do some hacking ;)

i cant use pointers and malloc
and it doesnt need to ask for more numbers
if not all numbers were entered it needs to return 0
if i enter 5 numbers it needs to return 0
if i enter letter like "hgm sfs" it doesnt return error and stop
it asks for more numbers instead

but here in every case it doesnt return an error massage or function return 0.
how to replace that??

i cant see why it stays on the same index
after it converts one number
loc=rid_next( buf,index,0); return the index where the number stops
loc=nex_num(buf,loc); returns the index where the spaces end(start of the next one)
i debugged it
and i cant see why i get the same index over and over
??

Code:

---



#include <stdio.h>
int nex_num(char buf[],int index);
int rid_next(char buf[],int index,int x);
void spin(char buf[],int arr[],int index,int num);
int one_num(char buf[],int index,int start);
int rid(char buf[],int index,int x);
int main()
{
       
        int arr[2];
    char buf[] ="-000123                143                ";

        spin(buf,arr,0,0);
        printf("%d %d\n",arr[0],arr[1]);
return 0;
}
void spin(char buf[],int arr[],int index,int num)
{

        int loc;
   
        if (buf[index]=='\0')
        {
      return;
        }
        arr[num]=one_num(buf,index, index);
        loc=rid_next( buf,index,0);
        loc=nex_num(buf,loc);
    spin(buf,arr,loc,num+1);
}

int one_num(char buf[],int index,int start)
{
int y=1,x = 0;
 
        if(buf[start]=='-')
    {
        y=-1;
                index++;
      }
        if(buf[start]=='+')
    {
        index++;
      }
        x=rid(buf,index,0)*y;
return x;

}

int rid(char buf[],int index,int x)
{
if ((buf[index]<'0')||(buf[index]>'9'))
{
return x;
}
  x *= 10;
  x += buf[index]-'0';
 
return rid(buf,index+1,x);

}

int nex_num(char buf[],int index)
{
  if ((buf[index]>='0')&&(buf[index]<='9'))
  {
      return index;
    }
 
return nex_num(buf,index+1);

}
int rid_next(char buf[],int index,int x)
{
    if ((buf[index]<'0')||(buf[index]>'9'))
    {
        return index;
    }
 
    return rid(buf,index+1,x);

}

---

Quote:

---

and i cant see why i get the same index over and over

---

I think I explained why in an earlier post:

Quote:

---

your rid_next() doesn't work because you want it to return the index following the first token read, and to do that you use rid() which does the job but returns the converted value (token to integer), and not an index, so you simply can't use rid() in rid_next(). Either you recode rid_next() as rid() but returning an index or you modify rid() to keep a track of the last index used.

---

i fixed it thanks :)