Highlight Source Codes in Web Pages

Examples of source codes in web pages are important for educational purposes. But showing them in a textarea can reduce readability. GNU Source-highlight presents a practical solutions for this.

Ubuntu users can download this using:

sudo apt-get install source-highlight

and the usage is like this:

source-highlight filename

If the filename is blah.extension, source-highlight creates blah.extension.html file in the same directory of filename.

The example C code below is about using sockets in POSIX type systems:

/*
** client.c -- a stream socket client demo
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>

#include <arpa/inet.h>

#define PORT "3490" // the port client will be connecting to 

#define MAXDATASIZE 100 // max number of bytes we can get at once 

// get sockaddr, IPv4 or IPv6:
void *get_in_addr(struct sockaddr *sa)
{
 if (sa->sa_family == AF_INET) {
  return &(((struct sockaddr_in*)sa)->sin_addr);
 }

 return &(((struct sockaddr_in6*)sa)->sin6_addr);
}

int main(int argc, char *argv[])
{
 int sockfd, numbytes;  
 char buf[MAXDATASIZE];
 struct addrinfo hints, *servinfo, *p;
 int rv;
 char s[INET6_ADDRSTRLEN];

 if (argc != 2) {
     fprintf(stderr,"usage: client hostname\n");
     exit(1);
 }

 memset(&hints, 0, sizeof hints);
 hints.ai_family = AF_UNSPEC;
 hints.ai_socktype = SOCK_STREAM;

 if ((rv = getaddrinfo(argv[1], PORT, &hints, &servinfo)) != 0) {
  fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
  return 1;
 }

 // loop through all the results and connect to the first we can
 for(p = servinfo; p != NULL; p = p->ai_next) {
  if ((sockfd = socket(p->ai_family, p->ai_socktype,
    p->ai_protocol)) == -1) {
   perror("client: socket");
   continue;
  }

  if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
   close(sockfd);
   perror("client: connect");
   continue;
  }

  break;
 }

 if (p == NULL) {
  fprintf(stderr, "client: failed to connect\n");
  return 2;
 }

 inet_ntop(p->ai_family, get_in_addr((struct sockaddr *)p->ai_addr),
   s, sizeof s);
 printf("client: connecting to %s\n", s);

 freeaddrinfo(servinfo); // all done with this structure

 if ((numbytes = recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
     perror("recv");
     exit(1);
 }

 buf[numbytes] = '\0';

 printf("client: received '%s'\n",buf);

 close(sockfd);

 return 0;
}

And this is a Java example about using Sockets in all platforms:

/**
 * SocketClient.java
 * Copyright (c) 2002 by Dr. Herong Yang
 */
import java.io.*;
import java.net.*;
public class SocketClient {
   public static void main(String[] args) {
      BufferedReader in = new BufferedReader(new InputStreamReader(
         System.in));
      PrintStream out = System.out;    
      try {
         Socket c = new Socket("localhost",8888);
         printSocketInfo(c);
         BufferedWriter w = new BufferedWriter(new OutputStreamWriter(
            c.getOutputStream()));
         BufferedReader r = new BufferedReader(new InputStreamReader(
            c.getInputStream()));
         String m = null;
         while ((m=r.readLine())!= null) {
            out.println(m);
            m = in.readLine();
            w.write(m,0,m.length());
            w.newLine();
            w.flush();
         }
         w.close();
         r.close();
         c.close();
      } catch (IOException e) {
         System.err.println(e.toString());
      }
   }
   private static void printSocketInfo(Socket s) {
      System.out.println("Remote address = "
         +s.getInetAddress().toString());
      System.out.println("Remote port = "
         +s.getPort());
      System.out.println("Local socket address = "
         +s.getLocalSocketAddress().toString());
      System.out.println("Local address = "
         +s.getLocalAddress().toString());
      System.out.println("Local port = "
         +s.getLocalPort());
   }
}