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

char* rand_str(const int length) {
    const int n_len = 1 + length / sizeof(uint32_t);
    uint32_t * const n = malloc(n_len);
    const uint32_t mask_printable = 0x20202020; // make sure it's printable
    const uint32_t mask_ascii     = 0x7F7F7F7F; // keep within ASCII range
    // The shift is endianess-dependent. Right shift needed on little-endian.
    const uint32_t last_mask      = length % 4 ? mask_ascii >> 8*(4 - (length % 4)) : 0;

    for(int i = 0; i < n_len; i++) {
        n[i] = (uint32_t) ((int64_t) rand() - INT32_MIN);
        n[i] |= mask_printable;
        n[i] &= i == n_len - 1 ? last_mask : mask_ascii;
    }

    return (char*) n;
}

int main(int argc, char **argv) {
    srand(time(NULL));
    int len   = argc > 1 ? atoi(argv[1]) : 7;
    int count = argc > 2 ? atoi(argv[2]) : 1;
    char *s;
    for(int i = 0; i < count; i++) {
        s = rand_str(len);
        printf("%s\n", s);
        free(s);
    }
    return 0;
}