GCC table example

How produce a sound ( add lSDL2 at compilation)

#include <SDL2/SDL.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define SAMPLE_RATE 44100
#define AMPLITUDE 28000
#define FREQUENCY 440.0

void audio_callback(void *userdata, Uint8 *stream, int len) {
    Sint16 *samples = (Sint16 *)stream;
    int i;

for (i = 0; i < len / 2; ++i) {
        double t = (double)i / SAMPLE_RATE;
        samples[i] = AMPLITUDE * sin(2.0 * M_PI * FREQUENCY * t);
    }
}

int main() {
    if (SDL_Init(SDL_INIT_AUDIO) < 0) {
        fprintf(stderr, "SDL initialization failed: %s\n", SDL_GetError());
        return 1;
    }

SDL_AudioSpec want, have;
    SDL_zero(want);

want.freq = SAMPLE_RATE;
    want.format = AUDIO_S16SYS;
    want.channels = 1;
    want.samples = 4096;
    want.callback = audio_callback;

SDL_AudioDeviceID audioDeviceID = SDL_OpenAudioDevice(NULL, 0, &want, &have, 0);

if (audioDeviceID == 0) {
        fprintf(stderr, "Failed to open audio device: %s\n", SDL_GetError());
        SDL_Quit();
        return 1;
    }

SDL_PauseAudioDevice(audioDeviceID, 0);  // Unpause audio

printf("Press Enter to quit...\n");
    getchar();  // Wait for Enter key

SDL_CloseAudioDevice(audioDeviceID);
    SDL_Quit();

return 0;
}

How use mysql in C

#include <stdio.h>
#include <stdlib.h>
#include <mysql/mysql.h>

#define SERVER "localhost"
#define USER "your_username"
#define PASSWORD "your_password"
#define DATABASE "your_database"

int main() {
    MYSQL *conn;
    MYSQL_RES *res;
    MYSQL_ROW row;

conn = mysql_init(NULL);

if (conn == NULL) {
        fprintf(stderr, "mysql_init() failed\n");
        exit(1);
    }

if (mysql_real_connect(conn, SERVER, USER, PASSWORD, DATABASE, 0, NULL, 0) == NULL) {
        fprintf(stderr, "mysql_real_connect() failed: %s\n", mysql_error(conn));
        mysql_close(conn);
        exit(1);
    }

if (mysql_query(conn, "SELECT * FROM your_table")) {
        fprintf(stderr, "mysql_query() failed: %s\n", mysql_error(conn));
        mysql_close(conn);
        exit(1);
    }

res = mysql_store_result(conn);

if (res == NULL) {
        fprintf(stderr, "mysql_store_result() failed: %s\n", mysql_error(conn));
        mysql_close(conn);
        exit(1);
    }

while ((row = mysql_fetch_row(res)) != NULL) {
        printf("%s\t%s\t%s\n", row[0], row[1], row[2]); // Adjust the number of columns as needed
    }

mysql_free_result(res);
    mysql_close(conn);

return 0;
}

Echo server

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>

#define PORT 12345
#define MAX_BUFFER_SIZE 1024

int main() {
    int serverSocket, clientSocket;
    struct sockaddr_in serverAddress, clientAddress;
    socklen_t clientAddressLength = sizeof(clientAddress);
    char buffer[MAX_BUFFER_SIZE];

// Create a socket
    serverSocket = socket(AF_INET, SOCK_STREAM, 0);
    if (serverSocket == -1) {
        perror("Error creating socket");
        exit(EXIT_FAILURE);
    }

// Set up the server address struct
    memset(&serverAddress, 0, sizeof(serverAddress));
    serverAddress.sin_family = AF_INET;
    serverAddress.sin_addr.s_addr = INADDR_ANY;
    serverAddress.sin_port = htons(PORT);

// Bind the socket to the specified address and port
    if (bind(serverSocket, (struct sockaddr*)&serverAddress, sizeof(serverAddress)) == -1) {
        perror("Error binding socket");
        close(serverSocket);
        exit(EXIT_FAILURE);
    }

// Listen for incoming connections
    if (listen(serverSocket, 10) == -1) {
        perror("Error listening for connections");
        close(serverSocket);
        exit(EXIT_FAILURE);
    }

printf("Echo server is listening on port %d...\n", PORT);

while (1) {
        // Accept a connection from a client
        clientSocket = accept(serverSocket, (struct sockaddr*)&clientAddress, &clientAddressLength);
        if (clientSocket == -1) {
            perror("Error accepting connection");
            continue;
        }

printf("Accepted connection from %s:%d\n", inet_ntoa(clientAddress.sin_addr), ntohs(clientAddress.sin_port));

// Receive and echo back data
        ssize_t bytesRead;
        while ((bytesRead = recv(clientSocket, buffer, sizeof(buffer), 0)) > 0) {
            // Echo back the received data
            send(clientSocket, buffer, bytesRead, 0);
        }

if (bytesRead == 0) {
            // Connection closed by the client
            printf("Connection closed by %s:%d\n", inet_ntoa(clientAddress.sin_addr), ntohs(clientAddress.sin_port));
        } else if (bytesRead == -1) {
            // Error receiving data
            perror("Error receiving data");
        }

// Close the client socket
        close(clientSocket);
    }

// Close the server socket
    close(serverSocket);

return 0;
}