lex program for display content of text file on output screen with a word “Hello” is replaced by “Hi”.

%{

  #include<stdio.h>

  int count=0;

%}

%%

[hH][Ee][Ll][Ll][oO] printf("HI");

%%

int main()

{

  FILE *fp;

  fp=fopen("5.txt","r");

  if(fp==NULL)

  {

       printf("Error");

  return 0;

  }

  yyin=fp;

  yylex();

}

ScreenShot: