linux makeFile的问题
makefile：

#makefile to run TCPEchoClient4.c TCPEchoServer4.c UDPEchoClient.c UDPEchoServer.c
TCPEchoServer4 :TCPEchoServer4.o
gcc -o TCPEchoServer4 TCPEchoServer4.o 
TCPEchoServer4.o:TCPEchoServer4.c 
gcc -c TCPEchoServer4.c 


Practical.h：

#ifndef PRACTICAL_H_
#define PRACTICAL_H_

#include <stdbool.h>
#include <stdio.h>
#include <sys/socket.h>

// Handle error with user msg
void DieWithUserMessage(const char *msg, const char *detail);
// Handle error with sys msg
void DieWithSystemMessage(const char *msg);
// Print socket address
void PrintSocketAddress(const struct sockaddr *address, FILE *stream);
// Test socket address equality
bool SockAddrsEqual(const struct sockaddr *addr1, const struct sockaddr *addr2);
// Create, bind, and listen a new TCP server socket
int SetupTCPServerSocket(const char *service);
// Accept a new TCP connection on a server socket
int AcceptTCPConnection(int servSock);
// Handle new TCP client
void HandleTCPClient(int clntSocket);
// Create and connect a new TCP client socket
int SetupTCPClientSocket(const char *server, const char *service);

enum sizeConstants {
  MAXSTRINGLENGTH = 128,
  BUFSIZE = 512,
};

#endif // PRACTICAL_H_




TCPEchoServer4.c


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "Practical.h"

static const int MAXPENDING = 5; // Maximum outstanding connection requests

int main(int argc, char *argv[]) {

  if (argc != 2) // Test for correct number of arguments
  DieWithUserMessage("Parameter(s)", "<Server Port>");

  in_port_t servPort = atoi(argv[1]); // First arg: local port

  // Create socket for incoming connections
  int servSock; // Socket descriptor for server
  if ((servSock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
  DieWithSystemMessage("socket() failed");

  // Construct local address structure
  struct sockaddr_in servAddr; // Local address
  memset(&servAddr, 0, sizeof(servAddr)); // Zero out structure
  servAddr.sin_family = AF_INET; // IPv4 address family
  servAddr.sin_addr.s_addr = htonl(INADDR_ANY); // Any incoming interface
  servAddr.sin_port = htons(servPort); // Local port

  // Bind to the local address
  if (bind(servSock, (struct sockaddr*) &servAddr, sizeof(servAddr)) < 0)
  DieWithSystemMessage("bind() failed");

  // Mark the socket so it will listen for incoming connections
  if (listen(servSock, MAXPENDING) < 0)
  DieWithSystemMessage("listen() failed");

  for (;;) { // Run forever
  struct sockaddr_in clntAddr; // Client address
  // Set length of client address structure (in-out parameter)
  socklen_t clntAddrLen = sizeof(clntAddr);

  // Wait for a client to connect
  int clntSock = accept(servSock, (struct sockaddr *) &clntAddr, &clntAddrLen);
  if (clntSock < 0)
  DieWithSystemMessage("accept() failed");

  // clntSock is connected to a client!

  char clntName[INET_ADDRSTRLEN]; // String to contain client address
  if (inet_ntop(AF_INET, &clntAddr.sin_addr.s_addr