tcp socket one increase server with multi thread c++11

multithread_increase_server.cpp

#include <cstdio>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <iostream>
#include <thread>

using namespace std;

void error(const char *message){
	perror(message);
	exit(1);
}

void increase_thread(void* lp){
	int *client_socket = (int*)lp;
	int check = 0;
	int output = 0;
	while(true){
		char buffer[256] = { 0 };
		check = read(*client_socket,buffer,256);
		if(check <= 0) {
			cout << "disconnect, client exited." << endl;
			close(*client_socket);
			return;
		}else if(string("exit").compare(buffer) == 0){
			cout << "client exited." << endl;
			close(*client_socket);
			return;
		}else if(string("shutdown").compare(buffer) == 0){
			cout << "server will shutdown." << endl;
			write(*client_socket,"shutdown",9);
			close(*client_socket);
			terminate();
			return;
		}
		string message;
		try {
			output = stoi(buffer) + 1;
			cout<<"client: "<<buffer<<endl;
			cout<<"result: "<<output<<endl;
			message=to_string(output);
		} catch(...) {
			message="Try again, input number.";
		}
		check=write(*client_socket,message.c_str(),message.length());
		if(check<0){
			cout << "disconnect, client exited." << endl;
			close(*client_socket);
			return;
		}
	}
}
int main(int argc,char **argv){
		
	if(argc<2)	error("argument is port.");

	int server_socket;
	int *client_socket;
	int port;
	socklen_t client_socket_length;
	struct sockaddr_in server_addr,client_addr;
	int queue_length;
	int check;
	
	port=atoi(argv[1]);
	queue_length=128;  

	server_socket=socket(AF_INET,SOCK_STREAM,0);
	if(server_socket<0)	error("error occurs in opening server_socket");

	server_addr.sin_family=AF_INET;
	server_addr.sin_addr.s_addr=INADDR_ANY;
	server_addr.sin_port=htons(port);        

	check = bind(server_socket,(struct sockaddr *)&server_addr,sizeof(server_addr));
	if(check<0) error("error occurs in binding");        
	
	check = listen(server_socket,queue_length);
	if(check<0) error("error occurs in listening");      

	while(true){
		client_socket_length=sizeof(client_addr);
		client_socket=new int;
		*client_socket = accept(server_socket,(struct sockaddr *)&client_addr,&client_socket_length);

		if(*client_socket<0){
			error("error occurs in accepting");
		} else {
			thread t(increase_thread,(void*)client_socket);
			t.detach();
			cout<<"client enters."<<endl; 
		}
	}
	return 0;
}