lex program to validate IP addresses from user specified file

%{

#include<stdio.h>

%}

%%

^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$ printf("Vaild IP Address");

[A-Za-z0-9.]* printf("Invalid IP Address");

%%

int main()

{

  FILE *fp;

  fp = fopen("ipaddress.txt", "r");

  if (fp == NULL) { printf("File not found"); }

  yyin = fp;

 yylex();

 return 0;

}

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