c소켓프로그래밍 으로 학점구하기

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
 
#define BUF_SIZE 1024
void error_handling();
 
 
 
int main(int argc, char *argv[])
{
	int serv_sock, clnt_sock;
	int korea[BUF_SIZE];
	int math[BUF_SIZE];
	int english[BUF_SIZE];
	float avg;
	char grade;
	int str_len, i;
	int tot;
 
 
	struct sockaddr_in serv_adr;
	struct sockaddr_in clnt_adr;
	socklen_t clnt_adr_sz;
 
	if (argc != 2) {
		printf("Usage : %s <port>\n", argv[0]);
		exit(1);
	}
 
	serv_sock = socket(PF_INET, SOCK_STREAM, 0);
	if (serv_sock == -1)
		error_handling("socket() error");
 
	memset(&serv_adr, 0, sizeof(serv_adr));
	serv_adr.sin_family = AF_INET;
	serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
	serv_adr.sin_port = htons(atoi(argv[1]));
 
	if (bind(serv_sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr)) == -1)
		error_handling("bind() error");
 
	if (listen(serv_sock, 5) == -1)
		error_handling("listen() error");
 
	clnt_adr_sz = sizeof(clnt_adr);
 
	for (i = 0; i<5; i++)
	{
		clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_adr, &clnt_adr_sz);
		if (clnt_sock == -1)
			error_handling("accept() error");
		else
			printf("Connected client %d \n", i + 1);
 
		while ((str_len = read(clnt_sock, korea, BUF_SIZE)) != 0)
		while ((str_len = read(clnt_sock, math, BUF_SIZE)) != 0)
		while ((str_len = read(clnt_sock, english, BUF_SIZE)) != 0)
			write(clnt_sock, (char*)&grade, str_len);
 
		for (i = 0; i < 1; i++) {
			tot = korea[i] + math[i] + english[i];
			avg = (float)tot / 3.0;
			printf("avg:%f\n", avg);
 
		}
 
 
		if (avg >= 90) {
			grade = 'A';
			printf("A", grade);
 
 
		}
 
		else if (avg >= 80) {
			grade = 'B';
			printf("B", grade);
 
 
 
		}
		else if (avg >= 70) {
			grade = 'C';
			printf("C", grade);
 
 
 
		}
		else if (avg >= 60) {
			grade = 'D';
			printf("D", grade);
 
 
 
		}
		else {
			grade = 'F';
			printf("F", grade);
 
 
		}
 
 
 
		close(clnt_sock);
	}
 
	close(serv_sock);
	return 0;
}
 
void error_handling(char *grade)
{
	fputs(grade, stderr);
	fputc('\n', stderr);
 
	exit(1);
 
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
 
#define BUF_SIZE 1024
void error_handling();
 
 
int main(int argc, char *argv[])
{
	int sock;
	int korea[BUF_SIZE];
	int math[BUF_SIZE];
	int english[BUF_SIZE];
	int tot;
	float avg;
	char grade;
	int str_len, i;
	struct sockaddr_in serv_adr;
 
	if (argc != 3) {
		printf("Usage : %s <IP> <port>\n", argv[0]);
		exit(1);
	}
 
	sock = socket(PF_INET, SOCK_STREAM, 0);
	if (sock == -1)
		error_handling("socket() error");
 
	memset(&serv_adr, 0, sizeof(serv_adr));
	serv_adr.sin_family = AF_INET;
	serv_adr.sin_addr.s_addr = inet_addr(argv[1]);
	serv_adr.sin_port = htons(atoi(argv[2]));
 
	if (connect(sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr)) == -1)
		error_handling("connect() error!");
	else
		puts("Connected...........");
 
 
	{
		fputs("Input korea (Q to quit): ", stdout);
		fgets(korea, BUF_SIZE, stdin);
 
		write(sock, korea, strlen(korea));
 
		fputs("Input math (Q to quit): ", stdout);
		fgets(math, BUF_SIZE, stdin);
 
		write(sock, math, strlen(math));
 
		fputs("Input english (Q to quit): ", stdout);
		fgets(english, BUF_SIZE, stdin);
 
		write(sock, english, strlen(english));
 
 
		read(sock,(char*) &grade, BUF_SIZE );
 
		printf("Your grade is :%c\n", grade);
 
 
	}
 
	close(sock);
	return 0;
}
 
void error_handling(char *grade)
{
	fputs(grade, stderr);
	fputc('\n', stderr);
 
	exit(1);
}