• Difficulty Level : Medium
• Last Updated : 02 Dec, 2021

Examples:

```Input  : 127.0.0.1
Output : 0x7f000001

Input  : 172.31.0.2
Output : 0xac1f0002

```

Explanation
using the Library function to convert the IP address to convert into the hexadecimal value we use ” arpa/inet.h “ header file. The inet_addr() function shall convert the string in the standard IPv4 dotted decimal notation, to an integer value suitable for use as an Internet address.

## C++

 `// C++ program for IP to``// hexadecimal conversion``#include ``#include ``#include ``using` `namespace` `std;`` ` `// function for reverse hexadecimal number``void` `reverse(``char``* str)``{``    ``// l for swap with index 2``    ``int` `l = 2;``    ``int` `r = ``strlen``(str) - 2;`` ` `    ``// swap with in two-2 pair``    ``while` `(l < r) {``        ``swap(str[l++], str[r++]);``        ``swap(str[l++], str[r]);``        ``r = r - 3;``    ``}``}`` ` `// function to conversion and print``// the hexadecimal value``void` `ipToHexa(``int` `addr)``{``    ``char` `str[15];`` ` `    ``// convert integer to string for reverse``    ``sprintf``(str, ``"0x%08x"``, addr);`` ` `    ``// reverse for get actual hexadecimal``    ``// number without reverse it will``    ``// print 0x0100007f for 127.0.0.1``    ``reverse(str);`` ` `    ``// print string``    ``cout << str << ``"\n"``;``}`` ` `// Driver code``int` `main()``{``    ``// The inet_addr() function  convert  string``    ``// in to standard IPv4 dotted decimal notation``    ``int` `addr = inet_addr(``"127.0.0.1"``);`` ` `    ``ipToHexa(addr);`` ` `    ``return` `0;``}`

Output:-

```0x7f000001
```

My Personal Notes arrow_drop_up