Loading...
More C Posts
// 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;}
#include <stdio.h>#include <assert.h>#include <signal.h>void myHandler(int iSig) {printf("In myHandler with argument %d\n", iSig);}int main() {void( * pfRet)(int) = signal(SIGINT, myHandler);assert(pfRet != SIG_ERR);printf("Entering an infinite loop\n");while (1) {printf(".");}return 0; // use CTRL+\ to exit}
#include <stdio.h>#include <stdlib.h>calculate(a, b)int a;int b;{printf("%d", a+b);}main(argc, argv)int argc;char** argv;{if(argc < 3){return 0;}calculate(atoi(argv[1]), atoi(argv[2]));}
#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;}
// 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 codeint main() {char buffer[MAXLINE];struct sockaddr_in servaddr;// Creating socket file descriptorint 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 secondtimeout.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 informationservaddr.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 toif(bytesRecieved >= 0){buffer[bytesRecieved] = '\0';printf("Recieved %s\n", buffer);}else{printf("Recieved nothing: Packet Dropped\n", buffer);}}close(sockfd);return 0;}
//===============replaceString.c===============#include "replaceString.h"//Normally I'd make a replaceStringMalloc to return a malloced string or a replaceStringMut to change the original string, but I'm not satisfied with those function names so it's best just to do to = (char*)malloc(replaceStringLength(from, replace, replacement)); replaceString(to, from, replace, replacement);//If this was c++, I'd have no problem just overloading replaceString//Returns the length of the resulting string (minus the null char)size_t replaceStringLength(const char* from, const char* replace, const char* replacement){size_t fromLength = strlen(from);size_t replaceLength = strlen(replace);size_t replacementLength = strlen(replacement);size_t fromEndIt = 0;size_t toLength = 0;while(fromEndIt < fromLength){int replaceIt = 0;while(replaceIt < replaceLength && (fromEndIt+replaceIt) < fromLength && from[fromEndIt + replaceIt] == replace[replaceIt]){++replaceIt;}if(replaceIt == replaceLength){//Update from buffer iterator positionstoLength += (fromEndIt + replacementLength);from += (fromEndIt + replaceLength);fromEndIt = 0;continue;}++fromEndIt;}toLength += fromEndIt;return toLength;}//Baller replaceString by Leif Messinger//Needs null terminated from, replace, and replacement strings as well as a large block of memory to store the result.void replaceString(char* to, const char* from, const char* replace, const char* replacement){size_t fromLength = strlen(from);size_t replaceLength = strlen(replace);size_t replacementLength = strlen(replacement);size_t fromEndIt = 0;while(fromEndIt < fromLength){int replaceIt = 0;while(replaceIt < replaceLength && (fromEndIt+replaceIt) < fromLength && from[fromEndIt + replaceIt] == replace[replaceIt]){++replaceIt;}if(replaceIt == replaceLength){//Copy the string before the matched bitmemcpyToAndShiftPointers(to, from, fromEndIt);//Copy the replacement toomemcpyToAndShiftPointer(to, replacement, replacementLength);//Update from buffer iterator positionsfrom += replaceLength;fromEndIt = 0;continue; //I don't want this thing to get incremented again}++fromEndIt;}//Copy the rest of the unmatched stringmemcpyToAndShiftPointer(to, from, fromEndIt);to[0] = '\0'; //Should work}//===============replaceString.h===============#ifndef REPLACE_STRING_H#define REPLACE_STRING_H#include <string.h>#define memcpyToAndShiftPointer(to,from,n); memcpy((to),(from),(n)); (to) += (n);#define memcpyToAndShiftPointers(to,from,n); memcpy((to),(from),(n)); (to) += (n); (from) += n;//Normally I'd make a replaceStringMalloc to return a malloced string or a replaceStringMut to change the original string, but I'm not satisfied with those function names so it's best just to do to = (char*)malloc(replaceStringLength(from, replace, replacement)); replaceString(to, from, replace, replacement);//If this was c++, I'd have no problem just overloading replaceString//Returns the length of the resulting string (minus the null char)size_t replaceStringLength(const char* from, const char* replace, const char* replacement);//Baller replaceString by Leif Messinger//Needs null terminated from, replace, and replacement strings as well as a large block of memory to store the result.void replaceString(char* to, const char* from, const char* replace, const char* replacement);#endif//===============replaceStringMain.c===============#include <stdio.h>#include <stdlib.h>#include "replaceString.h"#define BUFFER_SIZE (1<<21) //About a mebibyte//There could be matches between buffers, so make sure the buffer size you set it to is good enough for your application. Basically as big as your input.//Replaces strings from sdtin, then outputs it to stdout//./a.out [[replace], [replacement]]...int main(int argc, char** argv){char* buffer1 = (char*) malloc(BUFFER_SIZE);char* buffer2 = (char*) malloc(BUFFER_SIZE);if(buffer1 == NULL || buffer2 == NULL){perror("You need a couple MBs of ram my boy");return 1;}while(!feof(stdin)){fread(buffer1, BUFFER_SIZE, 1, stdin);char* activeBuffer = buffer1;char* inactiveBuffer = buffer2;char* tmp;for(size_t i = 1; (i + 1) < argc; i += 2){//puts(activeBuffer);replaceString(inactiveBuffer, activeBuffer, argv[i], argv[i+1]);//Swap bufferstmp = activeBuffer;activeBuffer = inactiveBuffer;inactiveBuffer = tmp;}fputs(activeBuffer, stdout);}free(buffer1);free(buffer2);return 0;}