How do I Alphabetically sort each word in a sentence?

Question

I need to sort each word in a sentence alphabetically while keeping the words separate from one another. I am not allowed to use the strtok() function.

Sample input: I would really appreciate some help

Sample output: I dlouw aellry aaceeipprt emos ehlp

I have managed to sort the entire string alphabetically.Which gives me an output of: Iaaacdeeeeehillllmooppprrstuwy

I am not sure If I should nest my current code into a loop which would start over every time there is a space. Or if I need to read my string into a two-dimensional array and sort each word separately.

I am also not sure if it would make more sense to compare the values of each char or to count the occurrence of each letter within the string. I have a version of each which gives me the output shown above.

Thanks in advance.

Version comparing chars:

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

int main () {

    char str[100];

    printf("Please type a sentence :\n");
    scanf("%[^\n]s", str);

    printf("\nAlphabetical order:\n:);

    char temp;

    int i, j;
    int n = strlen(str);

    for (i = 0; i < n-1; i++) {
        for (j = i+1; j < n; j++) {
            if (str[i] > str[j]) {
                temp = str[i];
                str[i] = str[j];
                str[j] = temp1;
            }
        }
    }

    printf(str);

    return 0;
}

Version counting occurrences of each char:

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

int main () {

  char ch, input[100], output[100];
  int no[26] = {0}, n, c, t, x;

  printf("Please type a sentence:\n");
  scanf("%s", input);

  n = strlen(input);

  for (c = 0; c < n; c++)
  {
    ch = input[c] - 'a';
    no[ch]++;
  }

  t = 0;

  for (ch = 'a'; ch <= 'z'; ch++)
  {
    x = ch - 'a';

    for (c = 0; c < no[x]; c++)
    {
      output[t] = ch;
      t++
    }
  }
  output[t]  = '\0';

  printf("%s\n", output);

  return 0;

}

Answer 1

std::sort will sort any sequence you give it. Eg

std::sort(str.begin(),str.begin()+5);
std::sort(str.begin()+6,str.end());
std::cout<<str;

Should output Hello dlorw . You can put custom comparison operator if you want to treat upper case letter differently.

Now you only have to iterate over the words. Please don't randomly mix C++ and C.

Answer 2

The standard library has enough facilities for you not to need to write any loop of your own. See:

How do I tokenize a string in C++?

about working with words and

The C++ standard algorithms library

for sorting etc. Oh, you might also want to read up on iterators.

Answer 3

Read user input with fgets() . Validate success before attempting to use input.

char buffer[1024];
if (fgets(buffer, sizeof buffer, stdin)) {
  const char *s = buffer;

Search for letters. Use isalpha() .

  while (*s) {
    while (!isalpha((unsigned char)*s) && *s) {
      putchar(*s);
      s++;
    }
    const char *start = s;
    while (isalpha((unsigned char)*s)) {
      s++;
    }

Sort with qsort() and print using a precision. Now s does not need to be null character terminated. Avoid sizeof(type) and use sizeof *pointer as it is easier to code right, review and maintain.

    int len = s - start;
    qsort(start, len, sizeof *start, fcmp);
    printf("%.*s", len, start);
  }
}

fcmp() simply compares characters. The standard library tends to treat the value of char as the value once it is converted to unsigned char .

int fcmp(const void *va, const void *vb) {
  const unsigned char *a = va;
  const unsigned char *b = vb;
  return (*a > *b) - (*a < *b);
}

Code could have used return a - b; . The above is more idiomatic and never involves int overflow (Unlike those rare machines with CHAR_MAX > INT_MAX ).