fast stdin/stdout

#include <windows.h>
#include <stdio.h>

#define BUF_SIZE 4096

int main() {
    DWORD bytesRead;
    char buffer[BUF_SIZE];

    // Ensure stdin is in binary mode
    _setmode(_fileno(stdin), _O_BINARY);

    HANDLE hStdin = GetStdHandle(STD_INPUT_HANDLE);

    while (ReadFile(hStdin, buffer, BUF_SIZE, &bytesRead, NULL) && bytesRead > 0) {
        // Process buffer[0..bytesRead-1]
    }

    return 0;
}


#include <unistd.h>

#define BUF_SIZE 4096

int main() {
    char buffer[BUF_SIZE];
    ssize_t bytesRead;

    while ((bytesRead = read(STDIN_FILENO, buffer, BUF_SIZE)) > 0) {
        // Process buffer[0..bytesRead-1]
    }

    return 0;
}


#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#ifdef _WIN32
  #include <io.h>      // _setmode(), _fileno()
  #include <fcntl.h>   // _O_BINARY
  #include <windows.h> // for GetLastError()
#else
  #include <unistd.h>  // write(), STDOUT_FILENO, usleep()
  #include <errno.h>   // errno
#endif

// write_all: repeatedly write() or fwrite() until all bytes are out
static int write_all(const uint8_t *buf, size_t total) {
    size_t written = 0;
    while (written < total) {
  #ifdef _WIN32
        int n = _write(_fileno(stdout),
                       buf + written,
                       (unsigned int)(total - written));
        if (n < 0) {
            fprintf(stderr,
                    "write error: code %ld\n",
                    GetLastError());
            return -1;
        }
  #else
        ssize_t n = write(STDOUT_FILENO,
                          buf + written,
                          total - written);
        if (n < 0) {
            if (errno == EINTR) continue;  // retry on signal
            perror("write");
            return -1;
        }
  #endif
        written += (size_t)n;
    }
    return 0;
}

int main(void) {
    // Example: allocate a 100 MiB buffer and fill it with a pattern
    size_t bufsize = 100 * 1024 * 1024;
    uint8_t *buffer = malloc(bufsize);
    if (!buffer) {
        perror("malloc");
        return EXIT_FAILURE;
    }
    for (size_t i = 0; i < bufsize; i++)
        buffer[i] = (uint8_t)(i & 0xFF);

  #ifdef _WIN32
    // Switch stdout to binary mode on Windows
    if (_setmode(_fileno(stdout), _O_BINARY) == -1) {
        fprintf(stderr, "failed to set stdout to binary mode\n");
        free(buffer);
        return EXIT_FAILURE;
    }
  #endif

    if (write_all(buffer, bufsize) != 0) {
        free(buffer);
        return EXIT_FAILURE;
    }

    // Optionally flush to ensure all data is handed off
    fflush(stdout);

    free(buffer);
    return EXIT_SUCCESS;
}