如何在类里传递字符串

C++实现 socket 传输任意字符串，在网上看到了许多很不错的代码，但大都是一端发送字符串，另外一端循环接收字符串，并没有对字符串的长度进行比较，试想：若在传完字符串后，还有其他的数据传送，那么在这样的情况下，接收端循环接收字符串就存在很大的弊端，因此在这里实现的是先将字符串的长度传送到接收端，而后紧接着传输字符串本身，这样在接收端就能先接收到字符串的长度，然后根据接收的长度接收字符串本身的数据。

客户端实现如下：

client.cpp

1. 
   
2. #include <iostream>
3. #include <;
4. #include <string>
5. #include <;
6. #include "TCPClient.h"
8. TCPClient tcp;
10. using namespace std;
12. void sig_exit(int s)
13. {
14. ();
15. exit(0);
16. }
18. int main(int argc, char *argv[])
19. {
20. string message;
21. getline(cin,message);
23. signal(SIGINT, sig_exit);
25. ("127.0.0.1",11999);
26. (message);
27. string rec = ();
28. if( rec != "" )
29. {
30. cout << "Server Response:" << rec << endl;
31. }
32. return 0;
33. }

TCPClient.cpp

1. 
   
2. #include "TCPClient.h"
4. TCPClient::TCPClient(){
5. sock = -1;
6. port = 0;
7. address = "";
8. }
10. bool TCPClient::setup(string address , int port){
11. if(sock == -1)
12. {
13. sock = socket(AF_INET , SOCK_STREAM , 0);
14. if (sock == -1)
15. {
16. cout << "Could not create socket" << endl;
17. }
18. }
19. if(inet_addr()) == (unsigned)-1)
20. {
21. struct hostent *he;
22. struct in_addr **addr_list;
23. if ( (he = gethostbyname( addre() ) ) == NULL)
24. {
25. herror("gethostbyname");
26. cout<<"Failed to resolve hostname\n";
27. return false;
28. }
29. addr_list = (struct in_addr **) he->h_addr_list;
30. for(int i = 0; addr_list[i] != NULL; i++)
31. {
32. = *addr_list[i];
33. break;
34. }
35. }
36. else
37. {
38. .s_addr = inet_addr( addre() );
39. }
40. = AF_INET;
41. = htons( port );
42. if (connect(sock , (struct sockaddr *)&server , sizeof(server)) < 0)
43. {
44. perror("connect failed. Error");
45. return false;
46. }
47. return true;
48. }
50. bool TCPClient::Send(string data){
52. cout<< "the data is："<< data <<endl;
54. if(sock != -1) {
55. int length = da();
56. if(send(sock, &length, sizeof(int), 0 ) < 0 ){
57. cout << "Send length failed : " << endl;
58. return false;
59. }
61. if( send(sock , da() , da() , 0) < 0){
62. cout << "Send failed : " << data << endl;
63. return false;
64. }
65. }
66. else
67. return false;
68. return true;
69. }
71. string TCPClient::receive(int size){
72. int length = 0;
73. recv(sock,&length,sizeof(int),0);
74. char* message = (char*)malloc(length+1);
75. memset(message, 0, length+1);
76. recv(sock,message,length,0);
77. string reply = message;
78. free(message);
79. return reply;
80. }
82. void TCPClient::exit()
83. {
84. close( sock );
85. }

TCPClient.h

1. 
   
2. #ifndef TCP_CLIENT_H
3. #define TCP_CLIENT_H
5. #include <iostream>
6. #include <;
7. #include <;
8. #include <uni;
9. #include <;
10. #include <sy;
11. #include <sy;
12. #include <netine;
13. #include <arpa;
14. #include <ne;
15. #include <ne;
16. #include <vector>
17. #include "../Agen;
19. using namespace std;
21. class TCPClient
22. {
23. private:
24. int sock;
25. std::string address;
26. int port;
27. struct sockaddr_in server;
29. public:
30. TCPClient();
31. bool setup(string address, int port);
32. bool Send(string data);
33. string receive(int size = 4096);
34. string read();
35. void exit();
36. };
38. #endif

在Linux 下进行编译，其编译命令如下：

g++ -Wall -o client client.cpp TCPClient.cpp -std=c++11 -lpthread

服务端代码如下：

1. 
   
2. #include <iostream>
3. #include "TCPServer.h"
5. TCPServer tcp;
7. int main()
8. {
9. //设置服务器端口
10. (11999);
11. ();
12. return 0;
13. }

TCPClient.cpp

1. 
   
2. #include "TCPServer.h"
5. void* TCPServer::Task(void *arg)
6. {
7. int sock = (long)arg;
8. pthread_detach(pthread_self());
10. //接收客户端字符串
11. if(sock != -1){
12. int length = 0;
13. if(sizeof(int)!=recv(sock,&length,sizeof(int),0)){
14. printf("recv length error...");
15. }
17. char* message = (char*)malloc(length+1);//length + 1 是保证传输的字符串中结束符的存在
18. memset(message, 0 , length);//清空缓冲区的内容
19. if(length != recv(sock,message,length,0)){
20. printf("recv string error...");
21. }
23. //以下将收到的字符串加上 --from server!!! 后发送回客户端
24. string returnstr = message;
25. returnstr += " --from server!!!";
26. int returnstr_length = re();
27. send(sock, &returnstr_length, sizeof(int),0);//先将字符串的长度发送给客户端
28. send(sock,re(),re(),0);
29. }
30. return 0;
31. }
33. void TCPServer::setup(int port)
34. {
35. sockfd=socket(AF_INET,SOCK_STREAM,0);
36. memset(&serverAddress,0,sizeof(serverAddress));
37. ;
38. (INADDR_ANY);
39. (port);
40. bind(sockfd,(struct sockaddr *)&serverAddress, sizeof(serverAddress));
41. listen(sockfd,5);
42. }
44. void TCPServer::receive()
45. {
46. while(1)
47. {
48. socklen_t sosize = sizeof(clientAddress);
49. newsockfd = accept(sockfd,(struct sockaddr*)&clientAddress,&sosize);
50. inet_ntoa);
51. pthread_create(&serverThread,NULL,&Task,(void *)newsockfd);
52. }
53. close(sockfd);
54. close(newsockfd);
55. }

TCPClient.h

1. 
   
2. #ifndef TCP_SERVER_H
3. #define TCP_SERVER_H
5. #include <iostream>
6. #include <;
7. #include <;
8. #include <;
9. #include <sy;
10. #include <sy;
11. #include <netine;
12. #include <;
13. #include <arpa;
14. #include <;
15. #include <uni;
17. using namespace std;
19. #define MAXPACKETSIZE 4096
21. class TCPServer
22. {
23. public:
24. int sockfd, newsockfd, n, pid;
25. struct sockaddr_in serverAddress;
26. struct sockaddr_in clientAddress;
27. pthread_t serverThread;
29. void setup(int port);
30. void receive();
32. private:
33. static void * Task(void * argv);
34. };
35. #endif

Server 端编译的命令如下：

g++ -Wall -o server TCPServer.cpp -std=c++11 -lpthread

最后实现的效果如下所示：