Thread: sorting array

You've reached your objective. The reason it's doubling every letter is because your string has 2 of each letter in it. Are you saying that your objective is also to eliminate duplicates or...?

>my objective is to sort the string, but the letters can't be duplicated
The simplest solution is to sort the string, then remove adjacent duplicates:

Code:

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

void sort(char str[])
{
  int i, j;
  char save;

  if (str[0] == '\0')
    return;

  for (i = 1; str[i] != '\0'; i++) {
    save = str[i];
    for (j = i; j >= 1 && save < str[j - 1]; j--)
      str[j] = str[j - 1];
    str[j] = save;
  }
}

void unique(char str[])
{
  int i, j;

  for (i = 0; str[i] != '\0';) {
    if (str[i] == str[i + 1]) {
      for (j = i + 1; str[j] != '\0'; j++)
        str[j] = str[j + 1];
    }
    else
      ++i;
  }
}

int main(void)
{
  char str[] = "programming";

  sort(str);
  unique(str);
  puts(str);

  return 0;
}

Notice that I used an insertion sort instead of the bubble sort. It's shorter, easier to understand, and far more efficient in all but the most exceptional circumstances. Here's some homework for you:

1. Why does the sort function terminate if the first element is a null character?
2. What purpose does the save variable serve in my sort function?
3. Why is the increment section of the outer loop in unique empty?
4. Do either of these functions access indices outside of the string's boundaries?
5. Make sure that this pair of functions actually works for any input. Consider long strings of duplicates, duplicates at the front and back of the string, and a string with nothing but duplicates.

With that out of the way, can you think of any other ways to solve the problem? What I showed you is not the best solution by any stretch of the imagination.

Hlo al. i ned a prgm 2 do this

1. Why does the sort function terminate if the first element is a null character?
2. What purpose does the save variable serve in my sort function?
3. Why is the increment section of the outer loop in unique empty?
4. Do either of these functions access indices outside of the string's boundaries?
5. Make sure that this pair of functions actually works for any input. Consider long strings of duplicates, duplicates at the front and back of the string, and a string with nothing but duplicates.

With that out of the way, can you think of any other ways to solve the problem?


m n a hry. plz email me the prgm thx

Quzah.