vidmodes2

/*
    Build it with: gcc -o vidmodes vidmodes.c -Os -s -Wall -Wextra -lX11 -lXxf86vm
*/

#include <X11/Xlib.h>
#include <X11/extensions/xf86vmode.h>
#include <stdio.h>
#include <stdlib.h>

int main() {

    Display *d = XOpenDisplay(NULL);
    if (!d)
        return 1;

    int count;
    XF86VidModeModeInfo **modes;
    Bool ret = XF86VidModeGetAllModeLines(d, 0, &count, &modes);

    printf("Returned %u, %u modes\n", ret, count);

    int i;
    for (i = 0; i < count; i++) {
        printf("Mode %u: %ux%u %.2fHz, flags %#x\n",
            i, modes[i]->hdisplay, modes[i]->vdisplay,
            1000.0f * modes[i]->dotclock /
                ((float) modes[i]->htotal * modes[i]->vtotal),
            modes[i]->flags);
    }

    free(modes);

    XCloseDisplay(d);
    return 0;
}