rushs/tinyprintf/rotx/rotx.c


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#include <stdlib.h>
#include <unistd.h>

#define BUFFER_SIZE 10

int main(int argc, char **argv)
{
    if (argc != 2)
    {
        return 0;
    }

    int rot = atoi(argv[1]);
    int rod = rot;
    if (rot < 0)
    {
        rot = (rot % 26) + 26;
        rod = (rod % 10) + 10;
    }

    char buf[BUFFER_SIZE];
    ssize_t r;

    while ((r = read(STDIN_FILENO, buf, BUFFER_SIZE)))
    {
        if (r == -1)
        {
            return 1;
        }

        for (ssize_t i = 0; i < r; i++)
        {
            if (buf[i] >= 'a' && buf[i] <= 'z')
            {
                buf[i] = ((buf[i] - 'a') + rot) % 26 + 'a';
            }
            else if (buf[i] >= 'A' && buf[i] <= 'Z')
            {
                buf[i] = ((buf[i] - 'A') + rot) % 26 + 'A';
            }
            else if (buf[i] >= '0' && buf[i] <= '9')
            {
                buf[i] = ((buf[i] - '0') + rod) % 10 + '0';
            }
        }

        ssize_t w = write(STDOUT_FILENO, buf, r);
        while (w != r)
        {
            w += write(STDOUT_FILENO, buf, r);
            if (w == -1)
            {
                return 1;
            }
        }
    }

    return 0;
}