Substring in c programming, c substring

C substring code

#include <stdio.h>

#include<conio.h>

#include <malloc.h>

char* substring(char*, int, int);

void main() 

{

   char string[100], *pointer;

   int position, length;

   clrscr();

   printf("Enter a string\n");

   gets(string);

   printf("Enter the position and length of substring\n");

   scanf("%d%d",&position, &length);

   pointer = substring( string, position, length);

   printf("Required substring is \"%s\"\n", pointer);

   free(pointer);

   getch();

}

/*C substring function: It returns a pointer to the substring */

char *substring(char *string, int position, int length) 

{

   char *pointer;

   int c;

   pointer = malloc(length+1);

   if (pointer == NULL)

   {

      printf("Unable to allocate memory.\n");

      exit(EXIT_FAILURE);

   }

   for (c = 0 ; c < position -1 ; c++) 

   string++; 

   for (c = 0 ; c < length ; c++)

   {

      *(pointer+c) = *string;      

      string++;   

   }

  *(pointer+c) = '\0';

  return pointer;

}

Output of program:

C code for all substrings of a string

#include <stdio.h>

#include <string.h>

#include<conio.h>

#include <malloc.h>

char* substring(char*, int, int);

void main() 

{

   char string[100], *pointer;

   int position = 1, length = 1, temp, string_length;

   clrscr();

   printf("Enter a string\n");

   gets(string);

   temp = string_length = strlen(string);

   printf("Substring of \"%s\" are\n", string);

   while (position <= string_length)

   {

      while (length <= temp)

      {

         pointer = substring(string, position, length);

         printf("%s\n", pointer);

         free(pointer);

         length++;

      }

      temp--;

      position++;

      length = 1;

   }

  getch();

}

Output of program: