gistfile1.cpp

#include <cstdio>
#include <cstring>
extern "C" {
#include <unistd.h>
}

constexpr int row = 23;
constexpr int column = 80;

char backbuffer[2000];

char get(int x, int y)
{
    return backbuffer[column * y + x];
}

void set(int x, int y, char c)
{
    backbuffer[column * y + x] = c;
}

void init()
{
    memset(backbuffer, ' ', sizeof(backbuffer));
    backbuffer[row * column] = '\0';
}

int main(void)
{
    init();
    for (int i = 0; i < row; i++)
    {
        set(0, i, 'a' + i);
    }
    while (true)
    {
        printf("%s", backbuffer);
        fflush(stdout);
        usleep(1000000);
    }
    return 0;
}