expanding function

[Tool]

Write a function expand(s1,s2) that expands shorthand notations like a-z in the string s1 into the equivalent complete list abc...xyz in s2 . Allow for letters of either case and digits, and be prepared to handle cases like a-b-c and a-z0-9 and -a-z . Arrange that a leading or trailing - is taken literally.

How exactly am i supposed to handle a-b-c? Just print out abc?

And what about z-a. Should i print thise backwards, from z to a?

How about handling -a-z, how to handle this?

[laserlight]

How exactly am i supposed to handle a-b-c? Just print out abc?

Ask your teacher what "a-b-c" means. Certainly, printing out "abc" is one option, but another option is to regard it as an error.

And what about z-a. Should i print thise backwards, from z to a?

Again, ask your teacher what "z-a" means. It makes sense to print the letters from z to a in that order, but it could also make sense to print them from a to z, or to regard it as an error.

How about handling -a-z, how to handle this?

You could just check to see if the first (and/or last) character is a dash.

[Tool]

Well i wish i had a teacher, im just self studying from the C book.

I did write the code for this, based on another code i found and its output looked like this - see attachment.

Anyway, this is the code i wrote...

#include <stdio.h>
#include <stdlib.h>
#define MAX_SIZE 1024

void expand (char dest[], char s[])
{
     int x = 0, y, z = 0;
     
     while(s[x] !='\0')
     {
        if((x == 0 || s[x+1] == '\0') && s[x] == '-') /* first or last char is a dash */
           dest[z++] = s[x];
          
        else if(s[x] == '-')
        {
             if(s[x-1] >='0' && s[x-1] <='9')  /* checking left char */
             {
                 if(s[x+1] >='0' && s[x+1] <='9') /* checking right char */
                 {
                      if(s[x-1] < s[x+1])
                      {
                         for(y = s[x-1]; y <= s[x+1]; y++)
                         dest[z++] = y;
                      }
                      else if(s[x-1] == s[x+1])
                      dest[z++] = s[x-1];
                      else
                      {
                          for(y = s[x-1]; y>= s[x+1]; y--)
                          dest[z++] = y;
                      }
                      
                 }
                 else if((s[x+1]>='a' && s[x+1] <='z') || (s[x+1]>='A' && s[x+1] <='Z'))
                 printf("Mismatching argument to expand.\n");
                 else dest[z++] = s[x];
             }
             else if(s[x-1] >='a' && s[x-1] <='z')
             {
                  if(s[x+1] >='a' && s[x+1] <='z')
                  {
                       if(s[x-1] < s[x+1])
                       {
                            for(y = s[x-1]; y<=s[x+1]; y++)
                            dest[z++] = y;
                       }
                       else if(s[x-1] == s[x+1])
                       dest[z++] = s[x-1];
                       else
                       {
                           for(y = s[x-1]; y>=s[x+1]; y--)
                           dest[z++] = y;
                       }
                  }
                  else if((s[x+1] >='0' && s[x+1]<='9') || (s[x+1]>='A' && s[x+1] <='Z'))
                  printf("Mismatching argument to expand.\n");
                  else dest[z++] = s[x];
             }
             else if(s[x-1] >='A' && s[x-1] <='Z')
             {
                  if(s[x+1] >='A' && s[x+1] <='Z')
                  {
                       if(s[x-1] < s[x+1])
                       {
                              for(y = s[x-1]; y<=s[x+1]; y++)
                              dest[z++] = y;
                       }
                       else if(s[x-1] == s[x+1])
                       dest[z++] = s[x-1];
                       else
                       {
                           for(y = s[x-1]; y>=s[x+1]; y--)
                           dest[z++] = y;
                       }
                  }
                  else if((s[x+1] >='0' && s[x+1] <='9') || (s[x+1] >='a' && s[x+1] <='z'))
                  printf("Mismatching argument to expand.\n");
                  else dest[z++] = s[x];
             }
             else dest[z++] = s[x]; /* a leading -, just put it in the string */
        }
        else if(s[x+1] == '-') /* check if leading dash */
        {
             if((s[x] >='0' && s[x] <='9') || (s[x] >='a' && s[x] <='z') || (s[x] >='A' && s[x] <='Z'))
             ;
             else dest[z++] = s[x];
        }
        else if(s[x-1] != '-' && s[x+1] !='-') 
           dest[z++] = s[x];
      
        x++;  
     }
     dest[z] = '\0';
}

     
     
     
int main(int argc, char *argv[])
{
     
     char s[MAX_SIZE] = "-r-a--";
     char destination[MAX_SIZE];
     
     expand(destination, s);
     printf("%s", destination);
     
     putchar('\n');
     system("PAUSE");    
     return 0;
}