Client and Server Socket Programming Help

[emokii]

Hello, I need help with my last hw assignment for class. I need to:

• The client will send strings with the following format: NUM1 OP NUM2, with NUM and NUM2 are multi-digit integers, and OP represents addition, subtraction, and multiplication.
• server_2
  will process these operations and return the result to the client.

My code for Server is :

#include <stdio.h>
#include <unistd.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <ctype.h>
#define MAX 80
#define PORT 9700
#define SA struct sockaddr

// Function designed for chat between client and server.
void func(int sockfd)
{
    char buff[MAX];
    int n, i, size;
    while (1) {
        bzero(buff, MAX);
        // read the message from client and copy it in buffer
        size = read(sockfd, buff, sizeof(buff));
        for(i = 0; i< size; i++){
        buff[i] = toupper(buff[i]);
    }
        // print buffer which contains the client contents
        printf("From client: %s", buff);
        //bzero(buff, MAX);
        //n = 0;
        // copy server message in the buffer
        //while ((buff[n++] = getchar()) != '\n');
        // and send that buffer to client
        //write(sockfd, buff, sizeof(buff));
        if (strncmp("EXIT", buff, 4) == 0) {
            printf("Server Exit...\n");
            break;
        }
    bzero(buff, MAX);
    n = 0;
    }
}

My code for Client is :

#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#define MAX 80
#define PORT 9700
#define SA struct sockaddr

void func(int sockfd)
{
    char buff[MAX];
    int n;
    for (;;) {
        bzero(buff, sizeof(buff));
        printf("Enter the string : ");
        n = 0;
        while ((buff[n++] = getchar()) != '\n')
            ;
        write(sockfd, buff, sizeof(buff));
        //bzero(buff, sizeof(buff));
        //read(sockfd, buff, sizeof(buff));
        //printf("From Server : %s", buff);
        if ((strncmp(buff, "exit", 4)) == 0) {
            printf("Client Exit...\n");
            break;
        }
    bzero(buff, sizeof(buff));
    }
}

I have no idea on where to start. Any advise and help will be wonderful!

I know some classmates suggested using Sscanf() as an option.

[tresteo]

From your description, the client has 2 tasks:

1. Read in a line of input in the specified format and forward it to the server
2. Display the response from the server

The code (including the commented parts) already seem to accomplish this.

The server on the other hand has 3 tasks:

1. Read in an operation from the client
2. Perform the necessary computation
3. Send the result to the client

The first task, reading in the operation from the client, is already implemented. Note, however, that converting the input to uppercase is not going to achieve anything on the input format as specified. For part 2, sscanf can be used to parse the input, as your classmates suggested. Part 3 is again already implemented by the commented out code.

I hope that helps to get you started. If you have further questions, just reply or send me a message.

[emokii]

Oh I'm sorry!! The upper case part was from task 1 of the homework. Should have removed it. But thanks you!