C Program to find given IP Address belongs to which Class(A,B,C,D,E)

#include<iostream.h>

#include<conio.h>

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

int check_digit_dot(char ipstr[])

{

 for(int i=0;i<strlen(ipstr);i++)

 {

  if((ipstr[i]>=48 && ipstr[i]<=57)||(ipstr[i]=='.'))

  {

   //i++;

  }

  else

  {    return 0;   }

  }

   return 1;

}

int check_ip(char ipstr[])

{

 char temp[20];

 int a,num,dot=0,j=0,numcount=0;

 a=check_digit_dot(ipstr);

 temp[0]='\0';

 if(a==0)

  return 0;

  else

   {

    for(int i=0;i<=strlen(ipstr);i++)

    {

      if(ipstr[i]!='.')

       {

             temp[j]=ipstr[i];

             j++;

             temp[j]='\0';

       }

      else

       {

             num=atoi(temp);

            // cout<<"num="<<num<<"\n";

             dot++;

             if((num>=0 && num<=255) && strlen(temp)>0)

             {  numcount++; }

             //cout<<"numcount="<<numcount<<"\n";

             j=0;

             temp[j]='\0';

       }

    }

    // after last dot

    num=atoi(temp);

   // cout<<"num="<<num<<"\n";

    if ((num>=0 && num<=255) && strlen(temp)>0)

    { numcount++; }

   // cout<<"numcount="<<numcount<<"\n";

  }

  //cout<<"dots="<<dot<<"  numcount="<<numcount<<"\n";

  if(dot==3 && numcount==4)

    return 1;

  else

    return 0;

 }

 

void main()

{

 clrscr();

 char a[50],temp[50];

 int check,j=0,num;

 cout<<" enter ip address\n";

 cin>>a;

 check=check_ip(a);

 if(check==0)

 {

  cout<<"not valid ip address\n";

  }

  else

  {

   cout<<" valid  ip address\n";

   temp[0]='\0';

   for(int i=0;i<strlen(a);i++)

   {

    if(a[i]=='.')

     {     break;       }

    else

     {

      temp[j]=a[i];

      j++;

      temp[j]='\0';

     }

   }

    num=atoi(temp);

    cout<<"num:"<<num<<"\n";

    if((num>=0)&&(num<128))

    cout<<"given ip address is class A\n";

    else if((num>=128)&&(num<192))

    cout<<"given ip address is class B";

    else if((num>=192)&&(num<224))

    cout<<"given ip address is class C";

    else if((num>=224)&&(num<240))

    cout<<"given ip address is class D";

    else

    cout<<"given ip address is class E";

  }

  getch();

 }