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inner fork() variables

0 likes • Nov 19, 2022 • 2 views
C
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socketTCPClient.c

0 likes • Aug 5, 2023 • 0 views
C
// compile: gcc socketTCPClient.c -o socketTCPClient.out
// usage : ./socketTCPClient.out port
// Doesn't send anything, just connects and prints out the response from the server
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h>
int main(int argc, char *argv[]){
int sockfd = 0, n = 0, portno;
char recvBuff[1025];
struct sockaddr_in serv_addr;
memset(recvBuff, '0', sizeof(recvBuff));
if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){
printf("socket error\n");
exit(EXIT_FAILURE);
}
serv_addr.sin_family = AF_INET;
portno = atoi(argv[1]);
serv_addr.sin_port = htons(portno);
serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
if(connect(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0){
printf("connect error\n");
exit(EXIT_FAILURE);
}
while((n = read(sockfd, recvBuff, sizeof(recvBuff)-1)) > 0){
recvBuff[n] = 0;
if (fputs(recvBuff, stdout) == EOF)
{
printf("fputs error\n");
}
}
if(n < 0){
printf("read error\n");
}
return 0;
}

socketUDPClient.c

0 likes • Aug 5, 2023 • 1 view
C
// Server 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(){
int sockfd;
char buffer[MAXLINE];
char *hello = "Hello from server";
struct sockaddr_in servaddr, cliaddr;
// Creating socket file descriptor
if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
memset(&servaddr, 0, sizeof(servaddr));
memset(&cliaddr, 0, sizeof(cliaddr));
// Filling server information
servaddr.sin_family = AF_INET; // IPv4
servaddr.sin_addr.s_addr = INADDR_ANY;
servaddr.sin_port = htons(PORT);
// Bind the socket with the server address
if ( bind(sockfd, (const struct sockaddr *)&servaddr, sizeof(servaddr)) < 0 ){
perror("bind failed");
exit(EXIT_FAILURE);
}
int len, n;
len = sizeof(cliaddr); //len is value/result
n = recvfrom(sockfd, (char *)buffer, MAXLINE, MSG_WAITALL, ( struct sockaddr *) &cliaddr, &len);
buffer[n] = '\0';
printf("Client : %s\n", buffer);
sendto(sockfd, (const char *)hello, strlen(hello), MSG_CONFIRM, (const struct sockaddr *) &cliaddr, len);
printf("Hello message sent.\n");
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;
}

socketUDPServer.c

0 likes • Aug 5, 2023 • 2 views
C
// Server 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 RECIEVE_BUFFER_SIZE 1024
const char* responseMessage = "Hello from server";
// Driver code
int main() {
//Create a UDP socket
//int socket(int domain, int type, int protocol);
//Domain is the place where the data goes. AF_BLUETOOTH, AF_INET6, AF_UNIX is local communication between different programs
//Type is the type of connection, so connection based (TCP), connectionless (UDP) or somewhere in between or beyond
//Protocol is an enum or flags that give some more options specific to that type. For SOCK_STREAM, you can force it to use SCTP instead of TCP. For SOCK_RAW, it can give you control over the ip frame, and even the ethernet frame.
//So this function makes a file descriptor to an IPV4 UDP 'connection' with no options.
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
// Creating socket file descriptor
if ( sockfd < 0) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
struct sockaddr_in serverAddress;
memset(&serverAddress, 0, sizeof(serverAddress));
// Filling server information
serverAddress.sin_family = AF_INET; // IPv4
serverAddress.sin_addr.s_addr = INADDR_ANY;
serverAddress.sin_port = htons(PORT);
// Bind the socket with the server address
if(bind(sockfd, (const struct sockaddr*)&serverAddress, sizeof(serverAddress))){ //Bind returns 0 if succeeded, or -1 if failed. -1 is still true.
perror("bind failed");
exit(EXIT_FAILURE);
}
struct sockaddr_in clientAddress; unsigned int clientAddressSize = sizeof(clientAddress);
memset(&clientAddress, 0, clientAddressSize);
char buffer[RECIEVE_BUFFER_SIZE];
int bytesRecieved = recvfrom(sockfd, (char*)buffer, RECIEVE_BUFFER_SIZE, MSG_WAITALL, (struct sockaddr*) &clientAddress, &clientAddressSize); //sets clientAddress to the client's address and the new size
buffer[bytesRecieved] = '\0';
printf("Client : %s\n", buffer);
sendto(sockfd, (const char*)responseMessage, strlen(responseMessage), MSG_CONFIRM, (const struct sockaddr*) &clientAddress, clientAddressSize);
printf("Hello message sent.\n");
return 0;
}

wait() example

0 likes • Nov 19, 2022 • 0 views
C
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
int main() {
char * cmd[] = {
"who",
"ls",
"date"
};
int i;
while (1) {
printf("0=who 1=ls 2=date : ");
scanf("%d", & i);
if (fork() == 0) {
/* child */
execlp(cmd[i], cmd[i], (char * ) 0);
printf("execlp failed\n");
exit(1);
} else {
/* parent */
wait((int * ) 0);
printf("child finished\n");
}
} /* while */
} /* main */

Arduino Sound Demo

0 likes • Jan 4, 2022 • 1 view
C
//Leif Messinger
const int BUZZER_PIN = 8;
const int BUTTON_PIN = 2;
const int BUTTON_PINMODE = INPUT_PULLUP;
#define DEBOUNCE_DELAY 50
class Button{
private:
short buttonPin;
bool buttonState;
bool lastButtonState;
int lastDebounceTime;
public:
Button(short buttonPin): buttonState(HIGH), lastButtonState(LOW), lastDebounceTime(millis()){
this->buttonPin = buttonPin;
}
bool checkForPress(const bool desiredState){ //Returns true if button pressed
bool reading = (bool)digitalRead(buttonPin);
// check to see if you just pressed the button
// (i.e. the input went from LOW to HIGH), and you've waited long enough
// since the last press to ignore any noise:
// If the switch changed, due to noise or pressing:
if (reading != lastButtonState) {
// reset the debouncing timer
lastDebounceTime = millis();
}else if ((millis() - lastDebounceTime) > DEBOUNCE_DELAY) {
// whatever the reading is at, it's been there for longer than the debounce
// delay, so take it as the actual current state:
// if the button state has changed:
if (reading != buttonState) {
buttonState = reading;
// only toggle the LED if the new button state is HIGH
if (buttonState == desiredState) {
return true;
}
}
}
// save the reading. Next time through the loop, it'll be the lastButtonState:
lastButtonState = reading;
return false;
}
void waitForPress(const bool desiredState){
while(!checkForPress(desiredState));
}
};
class Note{
public:
short frequency; //Short max is ~ 30k, so way higher than you can hear
short lag; //Also 30k ms is 30 seconds
float sustainPercentage;
};
const short normalBeatLength = 500;
const short wholeNote = 4*normalBeatLength;
const short halfNote = 2*normalBeatLength;
const short dottedQuarterNote = normalBeatLength + (normalBeatLength / 2);
const short quarterNote = normalBeatLength;
const short dottedEighthNote = ((3 * normalBeatLength) / 4);
const short eighthNote = normalBeatLength/ 2;
const short sixteenthNote = normalBeatLength / 4;
const float normalSustainLength = .25;
void beep(const Note& note){ //It might go terribly wrong if you try to beep two tones at the same time.
tone(BUZZER_PIN, note.frequency);
delay(note.lag * note.sustainPercentage);
noTone(BUZZER_PIN);
delay(note.lag * (1.0 - note.sustainPercentage));
}
Note song[] = {
{(int)523.25, halfNote, normalSustainLength},
{(int)392, eighthNote, normalSustainLength},
{(int)523.25, quarterNote, normalSustainLength},
{(int)392, dottedEighthNote, normalSustainLength},
{(int)440.00, sixteenthNote, normalSustainLength},
{(int)493.88, quarterNote, normalSustainLength},
{(int)329.63, eighthNote, normalSustainLength},
{(int)329.63, eighthNote, normalSustainLength},
{(int)440.00, quarterNote, normalSustainLength},
{(int)392, dottedEighthNote, normalSustainLength},
{(int)349.23, sixteenthNote, normalSustainLength},
{(int)392, quarterNote, normalSustainLength},
{(int)261.63, dottedEighthNote, normalSustainLength},
{(int)261.63, sixteenthNote, normalSustainLength},
{(int)293.66, quarterNote, normalSustainLength},
{(int)293.66, dottedEighthNote, normalSustainLength},
{(int)329.63, sixteenthNote, normalSustainLength},
{(int)349.23, quarterNote, normalSustainLength},
{(int)349.23, dottedEighthNote, normalSustainLength},
{(int)392.00, sixteenthNote, normalSustainLength},
{(int)440.00, quarterNote, normalSustainLength},
{(int)493.88, eighthNote, normalSustainLength},
{(int)523.25, eighthNote, normalSustainLength},
{(int)587.33, dottedQuarterNote, normalSustainLength},
{(int)392, eighthNote, normalSustainLength},
{(int)659.25, quarterNote, normalSustainLength},
{(int)587.33, dottedEighthNote, normalSustainLength},
{(int)523.25, sixteenthNote, normalSustainLength},
{(int)587.33, quarterNote, normalSustainLength},
{(int)493.88, eighthNote, normalSustainLength},
{(int)392, eighthNote, normalSustainLength},
{(int)523.25, quarterNote, normalSustainLength},
{(int)493.88, dottedEighthNote, normalSustainLength},
{(int)440.00, sixteenthNote, normalSustainLength},
{(int)493.88, quarterNote, normalSustainLength},
{(int)329.63, eighthNote, normalSustainLength},
{(int)329.63, eighthNote, normalSustainLength},
{(int)440.00, quarterNote, normalSustainLength},
{(int)392, dottedEighthNote, normalSustainLength},
{(int)349.23, sixteenthNote, normalSustainLength},
{(int)392, quarterNote, normalSustainLength},
{(int)261.63, dottedEighthNote, normalSustainLength},
{(int)261.63, sixteenthNote, normalSustainLength},
{(int)523.25, quarterNote, normalSustainLength},
{(int)493.88, dottedEighthNote, normalSustainLength},
{(int)440.00, sixteenthNote, normalSustainLength},
{(int)392.00, halfNote, normalSustainLength * .5},
};
size_t songLength = (sizeof(song) / sizeof(Note));
void playSong(){
for(size_t pos = 0; pos < songLength; ++pos){
const Note& bruh = song[pos];
beep(bruh);
}
}
void setup() {
const int BUZZER_PIN = 8;
pinMode(BUZZER_PIN, OUTPUT);
pinMode(BUTTON_PIN, BUTTON_PINMODE);
playSong();
}
Button button(BUTTON_PIN);
void loop() {
button.waitForPress(LOW);
// read the state of the switch into a local variable:
playSong();
}