Question

A valid IPv4 address is of the form ###.###.###.###, where each number, separated by '.', is 8 bits [0, 255]. Create program that validates input string containing an IP address. Use C programming language.

- Remove any newline \n from input string

- The input prompt should say "Enter IP Address of your choosing: "

- If IP address is invalid, it should print "You entered invalid IP\n"

- If IP address is valid, it should print "You entered valid IP\n"

- Convert string to integer using atof

Example:

• Valid IP

    Enter IP Address of your choosing: 192.169.0.4

    You entered valid IP

• Invalid IP

    Enter IP Address of your choosing: 192.666.432.1122

    You entered invalid IP

Answer 1

//Compiled using gcc compiler

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
int validate_number(char *str) {
   while (*str) {
      if(!isdigit(*str)){ //if the character is not a number, return false
    
         return 0;
      }
      str++; //point to next character
   }
   return 1;
}
int validateip(char *ip) { //check whether the IP is valid or not
   int i, num, dots = 0;
   char *ptr;
   if (ip == NULL)
      return 0;
      ptr = strtok(ip, "."); //cut the string using dor delimiter
      if (ptr == NULL)
         return 0;
   while (ptr) {
      if (!validate_number(ptr)) //check whether the sub string is holding only number or not
         return 0;
         num = atoi(ptr); //convert substring to number
         if (num >= 0 && num <= 255) {
            ptr = strtok(NULL, "."); //cut the next part of the string
            if (ptr != NULL)
               dots++; //increase the dot count
         } else
            return 0;
    }
    if (dots != 3) //if the number of dots are not 3, return false
       return 0;
      return 1;
}
int main() {
   char ip[50],n;
   printf("Enter the ip address:");
   scanf("%s",ip);
   n=validateip(ip);
   if(n==1)
      printf("You entered valid IP\n");
   else
      printf("You entered invalid IP\n");

   }

OUTPUT