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harismuneerharismuneer
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‎.gitattributes

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# Auto detect text files and perform LF normalization
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* text=auto

‎LICENSE

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MIT License
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Copyright (c) 2019 harismuneer
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.

‎README.md

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# Check_In-Check_Out-System-UDP

‎code/attendance.txt

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5 15-4150 15-4155 15-9024 15-4120 15-6780

‎code/c_udp.out

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‎code/client.c

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/*
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UDP_Client. This Program will implement the Client Side for UDP_Socket Programming.
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It will get some data from user and will send to the server and as a reply from the
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server, it will get its data back.
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*/
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#include <stdio.h>
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#include <string.h>
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#include <sys/socket.h> //socket
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#include <arpa/inet.h> //inet_addr
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int main(void)
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{
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int socket_number = 5006;
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int socket_desc;
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struct sockaddr_in server_addr;
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char server_message[2000], client_message[2000];
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int server_struct_length = sizeof(server_addr);
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//Cleaning the Buffers
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memset(server_message,'\0',sizeof(server_message));
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memset(client_message,'\0',sizeof(client_message));
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//Creating Socket
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socket_desc = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
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if(socket_desc < 0)
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{
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printf("Could Not Create Socket. Error!!!!!\n");
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return -1;
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}
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printf("Socket Created\n");
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//Specifying the IP and Port of the server to connect
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server_addr.sin_family = AF_INET;
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server_addr.sin_port = htons(socket_number);
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server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
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//Get Input from the User
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printf("Enter Message: ");
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gets(client_message);
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//Send the message to Server
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if(sendto(socket_desc, client_message, strlen(client_message), 0, (struct sockaddr*)&server_addr, server_struct_length) < 0)
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{
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printf("Send Failed. Error!!!!\n");
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return -1;
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}
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//Receive the message back from the server
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if(recvfrom(socket_desc, server_message, sizeof(server_message),0, (struct sockaddr*)&server_addr, &server_struct_length) < 0)
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{
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printf("Receive Failed. Error!!!!!\n");
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return -1;
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}
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printf("Server Message: %s\n",server_message);
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memset(server_message,'\0',sizeof(server_message));
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memset(client_message,'\0',sizeof(client_message));
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//Closing the Socket
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close(socket_desc);
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return 0;
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}
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‎code/s_udp.out

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‎code/server.c

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/*
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UDP_Server. This Program will will create the Server side for UDP_Socket Programming.
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It will receive the data from the client and then send the same data back to client.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/socket.h> //socket
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#include <arpa/inet.h> //inet_addr
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int main(void)
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{
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int socket_number = 5006;
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int socket_desc;
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struct sockaddr_in server_addr, client_addr;
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char server_message[2000], client_message[2000];
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int client_struct_length = sizeof(client_addr);
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//Cleaning the Buffers
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memset(server_message,'\0',sizeof(server_message));
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memset(client_message,'\0',sizeof(client_message));
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//Creating Socket
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socket_desc = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
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if(socket_desc < 0)
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{
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printf("Could Not Create Socket. Error!!!!!\n");
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return -1;
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}
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printf("Socket Created\n");
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//Binding IP and Port to socket
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server_addr.sin_family = AF_INET;
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server_addr.sin_port = htons(socket_number);
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server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
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if(bind(socket_desc, (struct sockaddr*)&server_addr, sizeof(server_addr))<0)
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{
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printf("Bind Failed. Error!!!!!\n");
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return -1;
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}
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printf("Bind Done\n");
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//----------------------------------------------------------//
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//read from file and initialize the array
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FILE* fptr = fopen("attendance.txt", "r");
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int current_size = 0;
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fscanf(fptr, "%d", &current_size);
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//--read empty space if any--//
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//char buff[2];
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//fscanf(fptr, "%s", buff);
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//using pointers to efficiently manage memory
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char *strs[20];
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char temp_roll[15];
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int l = 0;
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for(; l<current_size; l++)
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{
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fscanf(fptr, "%s", temp_roll);
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strs[l] = malloc(strlen(temp_roll+1));
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strcpy(strs[l], temp_roll);
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}
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fclose(fptr);
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//----------------------------------------------------------//
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while (1)
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{
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int write_to_file = 0;
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printf("Listening for Messages...\n\n");
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//Receive the message from the client
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if (recvfrom(socket_desc, client_message, sizeof(client_message), 0, (struct sockaddr*) &client_addr,&client_struct_length) < 0)
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{
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printf("Receive Failed. Error!!!!!\n");
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return -1;
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}
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printf("Received Message from IP: %s and Port No: %i\n",inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));
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// get roll number
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char rollnum[15];
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strcpy(rollnum, client_message);
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rollnum[7] = '\0';
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int i = 0;
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int found = 0;
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int f_index = 0;
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for (i = 0; i < current_size; i++)
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{
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if(strcmp(strs[i], rollnum) == 0)
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{
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found = 1;
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f_index = i;
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break;
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}
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}
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// Check In Scenario
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if (client_message[8] == 'C' && client_message[9] == 'I')
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{
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// if it doesnt exist then allocate memory to it
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if (found == 0)
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{
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strs[current_size] = malloc(strlen(rollnum) + 1);
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strcpy(strs[current_size], rollnum);
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current_size++;
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strcpy(server_message, "Welcome Student ");
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strcat(server_message, rollnum);
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strcat(server_message, " !\n");
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write_to_file = 1;
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}
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else
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{
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strcpy(server_message, "You are already here.\n");
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}
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}
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// Check Out Scenario
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else if (client_message[8] == 'C' && client_message[9] == 'O')
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{
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// remove that student from array and move all students one place backwards
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if (found == 1)
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{
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int j = f_index;
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//moving all students one place back
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for(; j < current_size - 1;j++)
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{
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strcpy(strs[j], strs[j+1]);
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}
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// mark one place free now
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free (strs[current_size - 1]);
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current_size--;
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strcpy(server_message, "Goodbye Student ");
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strcat(server_message, rollnum);
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strcat(server_message, " ! Have a nice day!\n");
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write_to_file = 1;
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}
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else
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{
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strcpy(server_message, "You didn't check in today. Contact System Administrator.\n");
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}
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}
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else
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printf("Wrong Input Message\n");
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printf("Current Size is %d . ", current_size);
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if (current_size > 0)
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{
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//print all members in the array
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printf("Following students are present:\n");
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int c = 0;
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for(; c < current_size; c++)
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{
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printf(strs[c]);
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printf("\n");
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}
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}
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else
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printf("No student is present.\n");
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//Send the message back to client
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if (sendto(socket_desc, server_message, strlen(server_message), 0, (struct sockaddr*)&client_addr,client_struct_length)<0)
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{
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printf("Send Failed. Error!!!!!\n");
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return -1;
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}
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memset(server_message,'\0',sizeof(server_message));
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memset(client_message,'\0',sizeof(client_message));
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// write to file only when the array is modified
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if (write_to_file == 1)
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{
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//in case the server shuts down for some reason, write the array back to file for persistence of database
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fptr = fopen("attendance.txt", "w");
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// write current size of array to file
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char a_size[5];
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snprintf (a_size, sizeof(a_size), "%d",current_size);
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fputs (a_size, fptr);
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fputs (" ", fptr);
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int k = 0;
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for(; k < current_size; k++)
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{
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fputs(strs[k], fptr);
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fputs (" ", fptr);
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}
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fclose(fptr);
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}
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}
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//Closing the Socket
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close(socket_desc);
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return 0;
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}

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