Question

write a program to enter a string "Dhoni is better than sachin" .Replace dhoni with sachin and sachin with dhoni .... without using string replace function

Answer 1

It is not clear whether the program should be very simple and work only for the above given sentence... or, it should be a generic program for interchanging one word with another in a string (for one occurrence only).

I have written a generic program.. so it works.

#include <stdio.h>

#include <string.h>

 

int main(void) {

     char str[128]=" ", word1[100]="  ", word2[100]="  ", *w1, *w2;

     char outp[128]=" ";  int i, j,k, n, n1, n2, pos1=-1, pos2=-1 ;

 

     printf("Input string : ");    gets(str);

     printf("\ninput the first word : ");  gets(word1);

     printf("\ninput the 2nd word: "); gets(word2);

     n = strlen(&str[0]);   n1 = strlen(&word1[0]);  n2 = strlen(&word2[0]);

     w1 = &word1[0] ; w2= &word2[0];

         

     for (i=0; i< n ; i++) {  // find position of word1

         for (j=0; i+j < n && j < n1 && str[i+j] == w1[j]; j++) ;

         if (j == n1) {pos1 = i; break;}

     }

     for (i =0; i < n; i++) {  // find position of word2

         for (k=0; i+k < n && k < n2 && str[i+k] == w2[k] ; k++) ;

         if (k == n2) {pos2 = i; break;}

     }

 

     if (pos1 >=0 && pos2 >=0)  {  // both words r there.  replace words.

          if (pos2 < pos1) {  // make pos1 smaller , interchange

              int temp = pos1; pos1 = pos2; pos2 = temp;

              temp = n1 ; n1 = n2;  n2 = temp;

              char *t = w1;  w1 = w2; w2 = t;

          }

          for (i =0; i < pos1; i++) outp[i] = str[i]; 

          for (j=0; j < n2;  j++, i++) outp[i] = w2[j];

          for (j=pos1+n1; j < pos2 ; j++, i++) outp[i] = str[j]; 

          for (j=0; j < n1 ; j++, i++) outp[i] = w1[j]; 

          for (j=pos2+n2 ; j < n; j++, i++) outp[i] = str[j] ; 

          outp[i]= '\0';

     } // if

printf("\n:inp string : %s\n words: %s :: %s\n outp string: %s\n", str, word1, word2, outp);

            return 0;

}