C program to check whether the given two strings are anagram or not

What is Anagram?
If the characters in one string can be rearranged to form another string, then both the string are anagram to each other.

Example: Eat and Tea are anagram to each other.

Algorithm to check whether the given two strings are anagram:
Step 1:  Get the inputs string from the user.
String 1: William Shakespeare
String 2: I am a weakish speller

Step 2:  Skip the space in the given input string.
String 1: WilliamShakespeare
String 2: Iamaweakishspeller

Step 3: Convert uppercase characters to lowercase.
String 1: williamshakespeare
String 2: lamaweakishspeller

Step 4:  Sort the characters in both the strings.
String 1: aaaeeehiikllmprssw
String 2: aaaeeehiikllmprssw

Step 5:  Compare the resultant strings.  If both are same, then anagram.


Write a C program to check whether the given two strings are anagram or not.

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

  /*
   * skips white space in the given input string.  If
   * there's any uppercase characters in i/p string
   * convert it to lowercase
   */
  void skipSpace(char *str) {
        char *ptr1, *ptr2;

        /* ptr1 and ptr2 points to 1st character of i/p string */
        ptr1 = ptr2 = str;

        /* copy all characters in the i/p string except space */
        while (*ptr1 != '\0') {
                /* skip the space */
                if (*ptr1 == ' ') {
                        ptr1++;
                        continue;
                }
                /* uppercase characters to lowercase */
                if (*ptr1 >= 'A' && *ptr1 <= 'Z') {
                        /* skip spaces and copying characters  */
                        *ptr2++ = (*ptr1 - 'A') + 'a';
                        ptr1++;
                } else {
                        /* skip space and copying characters */
                        *ptr2++ = *ptr1++;
                }
        }

        /* null termination */
        *ptr2 = *ptr1;
        return;
  }

  /* sort the characters in the input string */

  void sortCharacters(char *str) {

        int i, j, ch;

        for (i = 0; i < strlen(str) - 1; i++) {

                ch = str[i];

                for (j = i + 1; j < strlen(str); j++) {

                        if (ch > str[j]) {

                                ch = str[j];

                                str[j] = str[i];

                                str[i] = ch;

                        }

                }

        }

        return;

  }

  int main() {

        char first[256], second[256];

        /* get the first input string from the user */

        printf("Enter your first input string:");

        fgets(first, 256, stdin);

        first[strlen(first) - 1] = '\0';

        /* get the second input string from the user */

        printf("Enter your second input string:");

        fgets(second, 256, stdin);

        second[strlen(second) - 1] = '\0';

        /*

         * skip the whitespace in the i/p strings &

         * convert uppercase to lowercase if any.

         */

        skipSpace(first);

        skipSpace(second);

        /* sort the characters in above processed string */

        sortCharacters(first);

        sortCharacters(second);

        /* check data in first and second char array are same */

        if (strcasecmp(first, second) == 0) {

                printf("Given Two String are Anagram!!\n");

        } else {

                printf("Give Two Strings are not Anagrams!!\n");

        }

        return 0;

  }

  Output:

  jp@jp-VirtualBox:~/$ ./a.out
  Enter your first input string:tea
  Enter your second input string:eat
  Given Two String are Anagram!!