DS 2 - OPERATIONS ON STRINGS

2. Design, Develop and Implement a Program in C for the following operationson Strings a. Read a main String (STR), a Pattern String (PAT) and a Replace String (REP) b. Perform Pattern Matching Operation: Find and Replace all occurrences of PAT in STR with REP if PAT exists in STR. Report suitable messages in case PAT does not exist in STR Support the program with functions for each of the above operations. Don't use Built-in functions.

patternmatching.c - PROGRAM

#include<stdio.h>

void main()
{
  char s[20],pat[20],rep[20],ans[30];
  int i,j,k,l,flag;
  printf("\nEnter string:");
  scanf("%s",s);
  printf("\nEnter pattern:");
  scanf("%s",pat);
  printf("\nEnter replacement:");
  scanf("%s",rep);
  for(i=0,k=0;s[i]!='\0';i++)
  {
    flag=1;
    for(j=0;pat[j]!='\0';j++)
      if(s[i+j]!=pat[j])
        flag=0;
    l=j;
    if(flag)
    {
      for(j=0;rep[j]!='\0';j++,k++)
        ans[k]=rep[j];
      i+=l-1;
    }
    else
      ans[k++]=s[i];
  }
  ans[k]='\0';
  printf("%s",ans);

}