/*

 * C program to Compare Two Strings using loops.

 */

#include <stdio.h>

int main ()

{

         int count1 = 0, count2 = 0, flag = 0, i;

         char string1[30], string2[30];

         printf ("Enter the First string\n");

         gets (string1);

         printf ("Enter the Second string\n");

         gets (string2);

         while (string1[count1] != '\0')

                  count1 ++;

         while (string2[count2] != '\0')

                  count2 ++;

         i = 0;

         while (string1[i] == string2[i] && string1[i] != '\0')

         {

                  i ++;

         }

         if (string1[i] > string2[i])

                  printf ("First string is greater than Second string\n");

         else if (string1[i] < string2[i])

                  printf("Second string is greater than First string\n");

         else

                  printf ("Both strings are EQUAL\n");

         return 0;

}

/*

 * C Program to Delete All Repeated Words in String

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

int main ()

{

         char str[100], word[100], twoD[10][30];

         int i = 0, j = 0, k = 0, len1 = 0, len2 = 0, l = 0;

         printf ("Enter the string\n");

         gets (str);

         // let us convert the string into 2D array

         for (i = 0; str[i] != '\0'; i++)

         {

                  if (str[i] == ' ')

                  {

                            twoD[k][j] = '\0';

                            k ++;

                            j = 0;

                  }

                  else

                  {

                            twoD[k][j] = str[i];

                            j ++;

                  }

         }

         twoD[k][j] = '\0';

         j = 0;

         for (i = 0; i < k; i++)

         {

                  int present = 0;

                  for (l = 1; l < k + 1; l++)

                  {

                            if (twoD[l][j] == '\0' || l == i)

                            {

                                     continue;

                            }

                            if (strcmp (twoD[i], twoD[l]) == 0) {

                                     twoD[l][j] = '\0';

                                     present = present + 1;

                            }

                  }

                  // if (present > 0)              | uncomment this `if` block if you

                  // {                             | want to remove all the occurrences

                  //       twoD[i][j] = '\0';   | of the words including the word

                  // }                             | itself.

         }

         j = 0;

         for (i = 0; i < k + 1; i++)

         {

                  if (twoD[i][j] == '\0')

                            continue;

                  else

                            printf ("%s ", twoD[i]);

         }

         printf ("\n");

         return 0;

}

/*

 * C Program to Replace all the Characters by Lowercase 

 */

#include <stdio.h>

#include <string.h>

int main()

{

   char string[1000];

   printf("Input a string to convert to lower case\n");

   gets(string);

   printf("Input string in lower case: %s\n",strlwr(string));

   return  0;

}

/* 

 * C Program to Find the Frequency of Substring in 

 * the given String

 */

#include <stdio.h>

#include <string.h>

void main()

{

    int count = 0, i, j = 0, k;

    char str[100], str1[20];

    printf("Enter the string:\n");

    scanf(" %[^\n]s", str);

    printf("Enter the substring to be matched:\n");

    scanf(" %[^\n]s", str1);

    k = strlen(str1);

    for (i = 0; str[i] != '\0'; i++)

    {

        while (str[i] == str[j])

        {

            j ++;

        }

        if (j == k)

        {

            count ++;

            j = 0;

        }

    } 

    printf("No of matches of substring in main string is: %d\n", count);

}

/*

 * C Program to Count the Number of Unique Words

 */

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

int main()

{

    int i = 0, e, j, d, k, space = 0;

    char a[50], b[15][20], c[15][20];

    printf("Read a string:\n");

    fflush(stdin);

    scanf("%[^\n]s", a);

    for (i = 0;a[i] != '\0';i++)        //loop to count no of words

    {

        if (a[i] =  = ' ')

            space++;

    }

    i = 0;

    for (j = 0;j<(space + 1);i++, j++)    //loop to store each word into an 2D array

    {

        k = 0;

        while (a[i] != '\0')

        {

            if (a[i] == ' ')

            {

                break;

            }

            else

            {

                b[j][k++] = a[i];

                i++;

            }

        }

        b[j][k] = '\0';

    }

    i = 0;

    strcpy(c[i], b[i]);

    for (e = 1;e <= j;e++)        //loop to check whether the string is already present in the 2D array or not

    {

        for (d = 0;d <= i;d++)

        {

            if (strcmp(c[i], b[e]) == 0)

                break;

            else

            {

                i++;

                strcpy(c[i], b[e]);

                break;

            }

        }

    }

    printf("\nNumber of unique words in %s are:%d", a, i);

    return 0;

}

/*

 * C Program to find the possible subsets of the String

 */

#include <stdio.h>

char string[50], n;

void subset(int, int, int);

int main()

{

    int i, len;

    printf("Enter the len of main set : ");

    scanf("%d", &len);

    printf("Enter the elements of main set : ");

    scanf("%s", string);

    n = len;

    printf("The subsets are :\n");

    for (i = 1;i <= n;i++)

        subset(0, 0, i);

}

/*Function to find the number of subsets in the given string*/

void subset(int start, int index, int num_sub)

{

    int i, j;

    if (index - start + 1  ==  num_sub)

    {

        if (num_sub  ==  1)

        {

            for (i = 0;i < n;i++)

                printf("%c\n", string[i]);

        }

        else

        {

            for (j = index;j < n;j++)

            {

                for (i = start;i < index;i++)

                    printf("%c", string[i]);

                printf("%c\n", string[j]);

            }

            if (start != n - num_sub)

                subset(start + 1, start + 1, num_sub);

        }

    }

    else

    {

        subset(start, index + 1, num_sub);

    }

}

/*

 * C Program to find the ascii value of a character

 */

#include <stdio.h>

int main()

{

    char ch;

    printf("Enter Character: ");

    scanf("%c",&ch);

    //Type Casting character to int

    int ascii = (int)ch;

    printf("Ascii Value of %c is %d",ch,ascii);

    return 0;

}

* 

 * C Program to find First and Last Occurrence of given 

 * Character in a String

 */

#include <stdio.h>

#include <string.h>

void main()

{

    int i, count = 0, pos1, pos2;

    char str[50], key, a[10];

    printf("enter the string\n");

    scanf(" %[^\n]s", str);

    printf("enter character to be searched\n");

    scanf(" %c", &key);

    for (i = 0;i <= strlen(str);i++)

    {

        if (key == str[i])

        {

            count++;

            if (count  == 1)

            {

                pos1 = i;

                pos2 = i;

                printf("%d\n", pos1 + 1);

            }

            else 

            {

                pos2 = i;

            }

        }

    }

    printf("%d\n", pos2 + 1);

}

enter the string

welcome to sanfoundry's c programming class!

enter character to be searched

m

6

34

/*

 * C Program to Implement a strpbrk() Function

 */

#include <stdio.h>

char* strpbrk(char *, char *);

int main()

{

    char string1[50], string2[50];

    char *pos;

    printf("Enter the String:\n");

    scanf(" %[^\n]s", string1);

    printf("\nEnter the Character Set:\n");

    scanf(" %[^\n]s", string2);

    pos=strpbrk(string1, string2);

    printf("%s", pos);

}

/* Locates First occurrence in string s1 of any character in string s2,

 * If a character from string s2 is found ,

 * a pointer to the character in string s1 is returned,

 * otherwise,  a NULL pointer is returned.

 */

char* strpbrk(char *string1, char *string2)

{

    int i, j, pos, flag = 0;

    for (i = 0; string1[i] != '\0';i++);

    pos = i;

    for (i = 0;string2[i] != '\0';i++)

    {

        for (j = 0;string1[j] != '\0';j++)

        {

            if (string2[i] == string1[j])

            {

                if (j <= pos)

                {

                    pos = j;   

                    flag = 1;   

                }

            }

         }       

    }

    if (flag == 1)

    {

        return &string1[pos];

    }

    else

    {

        return NULL;

    }

}