#include <string.h>
#include <stdio.h>
#include <errno.h>

#define NUMCORES 2
long g_CPUUsage[NUMCORES][4];

int main() {
    int coreFlags = 0;
    char buf[1024];
    FILE* fp;
    int i;

    if ((fp = fopen ("/proc/stat", "r")) == NULL) {
        fprintf (stderr, "couldn't open /proc/stat: %s\n", strerror (errno));
        return 1;
    }

    while (fgets (buf, sizeof buf, fp)) {
        int coreid;
        long coredata[4];
        if (sscanf (buf, "cpu%d %ld %ld %ld %ld", &coreid, &coredata[0],
            &coredata[1], &coredata[2], &coredata[3]) && coreid < NUMCORES)
        {
            memcpy (&g_CPUUsage[coreid][0], &coredata[0], sizeof coredata);
            coreFlags |= (1 << coreid);
        }
    }

    fclose (fp);

    if (coreFlags != (1 << NUMCORES) - 1) {
        fprintf (stderr, "error: insufficient data\n");
        return 1;
    } else
        for (i = 0; i < NUMCORES; ++i)
            printf ("Core %d: [%ld, %ld, %ld, %ld]\n", i, g_CPUUsage[i][0],
                g_CPUUsage[i][1], g_CPUUsage[i][2], g_CPUUsage[i][3]);

    return 0;
}