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signal() example

0 likes • Nov 19, 2022 • 0 views
C
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socketTCPServer.c

0 likes • Aug 5, 2023 • 0 views
C
// compile: gcc socketTCPServer.c -o socketTCPServer.out
// usage : ./socketTCPServer.out port
// Server
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
int main(int argc, char *argv[]){
int listenfd = 0, connfd = 0, cli_size, portno;
struct sockaddr_in serv_addr, cli_addr;
char sendBuff[1025];
if((listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1){
printf("socket error\n");
exit(EXIT_FAILURE);
}
memset(&serv_addr, '0', sizeof(serv_addr));
memset(sendBuff, '0', sizeof(sendBuff));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
portno = atoi(argv[1]);
serv_addr.sin_port = htons(portno);
const int on = 1;
setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
if(bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) == -1){
printf("bind error\n");
exit(EXIT_FAILURE);
}
if(listen(listenfd, 5) == -1){
printf("listen error\n");
exit(EXIT_FAILURE);
}
while(1){
cli_size = sizeof(cli_addr);
if((connfd = accept(listenfd, (struct sockaddr*)&cli_addr, &cli_size)) == -1){
printf("accept error\n");
exit(EXIT_FAILURE);
}
strcpy(sendBuff, "Server Message: SUCCESS\n");
write(connfd, sendBuff, strlen(sendBuff));
close(connfd);
sleep(1);
}
return 0;
}

pipe() example

0 likes • Nov 19, 2022 • 0 views
C
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#define READ 0 /* The index of the read end of the pipe */
#define WRITE 1 /* The index of the write end of the pipe */
char * phrase = "This goes in the pipe";
int main() {
int fd[2], bytesRead;
char message[100]; /* Parent process' message buffer */
pipe(fd); /* Create unnamed pipe */
if (fork() == 0) /* Child, writer */ {
close(fd[READ]); /* Close unused end */
write(fd[WRITE], phrase, strlen(phrase) + 1); /* Include NULL */
close(fd[WRITE]); /* Close used end */
} else /* Parent, reader */ {
close(fd[WRITE]); /* Close unused end */
bytesRead = read(fd[READ], message, 100);
printf("Parent just read %i bytes: %s\n", bytesRead, message);
close(fd[READ]); /* Close used end */
}
}

socketUDPPingClient.c

0 likes • Aug 5, 2023 • 0 views
C
// Client side implementation of UDP client-server model
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define PORT 8008
#define MAXLINE 1024
// Driver code
int main() {
char buffer[MAXLINE];
struct sockaddr_in servaddr;
// Creating socket file descriptor
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if ( sockfd < 0 ) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
struct timeval timeout;
timeout.tv_sec = 1; //Wait 1 second
timeout.tv_usec = 0;
if (setsockopt (sockfd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof timeout) < 0) perror("setsockopt failed\n");
if (setsockopt (sockfd, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof timeout) < 0) perror("setsockopt failed\n");
memset(&servaddr, 0, sizeof(servaddr));
// Filling server information
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
servaddr.sin_addr.s_addr = inet_addr("192.168.4.65");
for(int i = 0; i < 10; ++i){
char* message = "PING";
int sendStatus = sendto(sockfd, (const char *)message, strlen(message), MSG_CONFIRM, (const struct sockaddr *) &servaddr, sizeof(servaddr));
if(sendStatus >= 0){
printf("Sent PING\n");
}else{
printf("Send failed\n");
continue;
}
int len = sizeof(struct sockaddr_in);
int bytesRecieved = recvfrom(sockfd, (char *)buffer, MAXLINE, MSG_WAITALL, (struct sockaddr *) &servaddr, &len); //We can reuse servaddr because the port the server sends messages from is the same one we send to
if(bytesRecieved >= 0){
buffer[bytesRecieved] = '\0';
printf("Recieved %s\n", buffer);
}else{
printf("Recieved nothing: Packet Dropped\n", buffer);
}
}
close(sockfd);
return 0;
}

inner fork() variables

0 likes • Nov 19, 2022 • 2 views
C
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int glbvar = 6;
int main() {
int locvar = 88;
pid_t pid;
printf("Before fork()\n");
if ((pid = fork()) == 0) {
/* child */
glbvar++;
locvar++;
} else if (pid > 0) {
/* parent */
sleep(2);
} else
perror("fork error");
printf("pid=%d, glbvar=%d, locvar=%d\n", getpid(), glbvar, locvar);
return 0;
} /* end main */

fork() example

0 likes • Nov 19, 2022 • 1 view
C
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int main() {
pid_t pid; /* could be int */
int i;
pid = fork();
printf("PID=%d\n", pid);
if (pid > 0) {
/* parent */
for (i = 0; i < 10; i++)
printf("\t\t\tPARENT %d\n", i);
} else {
/* child */
for (i = 0; i < 10; i++)
printf("CHILD %d\n", i);
}
return 0;
}

Heavy Coin

0 likes • Oct 4, 2023 • 2 views
C
#include <stdio.h>
#include <stdlib.h>
// give an array of identical coins (ints), represented by 1's and one 2
// we can find the heavy coin (2) by summing the contents of the thirds
int sum_subarr(int arr[], int l, int r){
int sum = 0;
for(int i = l; i <= r; i++)
{
sum += arr[i];
}
return sum;
}
int heavy_coin(int arr[], int l, int r){
if(r == l)
{
return r;
}
int midl = l + (r - l)/3;
int midr = r - (r - l)/3;
int lw = sum_subarr(arr, l, midl);
int mw = sum_subarr(arr, midl + 1, midr);
if ( lw > mw )
{
return heavy_coin(arr, l, midl);
}
else if ( lw < mw )
{
return heavy_coin(arr, midl + 1, midr);
}
else
{
return heavy_coin(arr, midr + 1, r);
}
}
int main(int argc, char *argv[])
{
int arr[] = {1,1,1,1,2,1,1,1,1};
int l = 0;
int r = 8;
int res = -1;
res = heavy_coin(arr, l, r);
printf("Hevy coin is at index: %d\n", res);
return EXIT_SUCCESS;
}