C Program to display hostname and IP address Last Updated : 14 Oct, 2024 Comments Improve Suggest changes Like Article Like Report Method 1: There are many ways to find Hostname and IP address of a local machine. Here is a simple method to find hostname and IP address using C program. We will be using the following functions :- gethostname() : The gethostname function retrieves the standard host name for the local computer. gethostbyname() : The gethostbyname function retrieves host information corresponding to a host name from a host database. inet_ntoa() : The inet_ntoa function converts an (Ipv4) Internet network address into an ASCII string in Internet standard dotted-decimal format. C // C program to display hostname // and IP address #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <netdb.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> // Returns hostname for the local computer void checkHostName(int hostname) { if (hostname == -1) { perror("gethostname"); exit(1); } } // Returns host information corresponding to host name void checkHostEntry(struct hostent * hostentry) { if (hostentry == NULL) { perror("gethostbyname"); exit(1); } } // Converts space-delimited IPv4 addresses // to dotted-decimal format void checkIPbuffer(char *IPbuffer) { if (NULL == IPbuffer) { perror("inet_ntoa"); exit(1); } } // Driver code int main() { char hostbuffer[256]; char *IPbuffer; struct hostent *host_entry; int hostname; // To retrieve hostname hostname = gethostname(hostbuffer, sizeof(hostbuffer)); checkHostName(hostname); // To retrieve host information host_entry = gethostbyname(hostbuffer); checkHostEntry(host_entry); // To convert an Internet network // address into ASCII string IPbuffer = inet_ntoa(*((struct in_addr*) host_entry->h_addr_list[0])); printf("Hostname: %s\n", hostbuffer); printf("Host IP: %s", IPbuffer); return 0; } OutputHostname: 31811ca6b90f Host IP: 172.17.0.4Output varies machine to machineMethod 2: The hostname and IP address of a local machine can be found in a variety of ways. Here is a straightforward C programme to find hostname and IP address. The following operations will be used:- gethostname(): The gethostname method returns the local computer's default host name. gethostbyname(): This function extracts host data from a host database corresponding to a host name. The inet_ntoa function transforms a (Ipv4) Internet network address into an ASCII string using the dotted-decimal Internet standard. C // C++ program to display hostname // and IP address #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/socket.h> #include <arpa/inet.h> #include <netdb.h> // Function use int main() { char hostbuffer[256]; struct hostent *host_entry; int hostname; struct in_addr **addr_list; // retrieve hostname hostname = gethostname(hostbuffer, sizeof(hostbuffer)); if (hostname == -1) { perror("gethostname error"); exit(1); } printf("Hostname: %s\n", hostbuffer); // Retrieve IP addresses host_entry = gethostbyname(hostbuffer); if (host_entry == NULL) { perror("gethostbyname error"); exit(1); } addr_list = (struct in_addr **)host_entry->h_addr_list; for (int i = 0; addr_list[i] != NULL; i++) { printf("IP address %d: %s\n", i+1, inet_ntoa(*addr_list[i])); } return 0; } OutputHostname: bd15a44cb17c IP address 1: 172.17.0.3Time Complexity: O(n)Auxilitary Space: O(1) Comment More infoAdvertise with us Next Article C Program to display hostname and IP address S Smitha Dinesh Semwal Follow Improve Article Tags : Misc Computer Networks C Language C++ Practice Tags : CPPMisc Similar Reads Display Hostname and IP address in Python In networking applications, identifying the system running a program is important. 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