inner fork() variables
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// 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;}
// 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 codeint main(){int sockfd;char buffer[MAXLINE];char *hello = "Hello from server";struct sockaddr_in servaddr, cliaddr;// Creating socket file descriptorif ( (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 informationservaddr.sin_family = AF_INET; // IPv4servaddr.sin_addr.s_addr = INADDR_ANY;servaddr.sin_port = htons(PORT);// Bind the socket with the server addressif ( bind(sockfd, (const struct sockaddr *)&servaddr, sizeof(servaddr)) < 0 ){perror("bind failed");exit(EXIT_FAILURE);}int len, n;len = sizeof(cliaddr); //len is value/resultn = 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;}
#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 thirdsint 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;}
// 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 1024const char* responseMessage = "Hello from server";// Driver codeint 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 descriptorif ( sockfd < 0) {perror("socket creation failed");exit(EXIT_FAILURE);}struct sockaddr_in serverAddress;memset(&serverAddress, 0, sizeof(serverAddress));// Filling server informationserverAddress.sin_family = AF_INET; // IPv4serverAddress.sin_addr.s_addr = INADDR_ANY;serverAddress.sin_port = htons(PORT);// Bind the socket with the server addressif(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 sizebuffer[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;}
#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 */
//Leif Messingerconst int BUZZER_PIN = 8;const int BUTTON_PIN = 2;const int BUTTON_PINMODE = INPUT_PULLUP;#define DEBOUNCE_DELAY 50class 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 pressedbool 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 timerlastDebounceTime = 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 HIGHif (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 hearshort lag; //Also 30k ms is 30 secondsfloat 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();}