题目

请利用 setitimer() 和 sigaction() 函数编写一个小游戏，该游戏随机在 5 ~ 15 秒之内开始，开始后随机从 ’w’, ‘s’, ‘a’, ‘d’ 中选取 4 个字母显示在屏幕上，玩家需要迅速正确键入字母并回车以赢得并退出游戏，否则 3 秒后游戏将重新选取 4 个字母显示，无穷地循环下去。

点拨

源代码

#include <chrono>
#include <cstdio>
#include <cstring>
#include <fcntl.h>
#include <random>
#include <signal.h>
#include <sys/time.h>
#include <unistd.h>

using namespace std;
using namespace std::chrono;

using flag_t = int;

uniform_real_distribution<double> random_start_time(5, 15);
uniform_int_distribution<unsigned> random_char_pos(0, 3);
mt19937_64 re(high_resolution_clock::now().time_since_epoch().count());

const char chr[] = { "wsad" };

const __time_t time_limit_sec = 3;
const size_t letter_count = 4;
const size_t input_capacity = 1024;

const struct timeval waitintv = { time_limit_sec, 0 };
const struct timeval onceintv = { 0, 0 };
const struct itimerval itvw = { waitintv, waitintv };
const struct itimerval notimer = { onceintv, onceintv };

void game_start(int);
void lose_game(int);

const struct sigaction no_act = { nullptr, {}, 0, nullptr };
const struct sigaction start_act = { game_start, {}, 0, nullptr };
const struct sigaction lose_act = { lose_game, {}, 0, nullptr };

char required[letter_count + 2] = { "    \n" }, input[input_capacity];
bool won = false, again;

void game_start(int) {
    puts("GAME START\n");
}

void lose_game(int) {
    puts("YOU LOSE.\n");
    again = true;
}

int main() {
    flag_t flag = fcntl64(STDIN_FILENO, F_GETFL, 0);
    flag |= O_NONBLOCK;
    fcntl64(STDIN_FILENO, F_SETFL, flag);

    const struct timeval startintv = { random_start_time(re), 0 };
    const struct itimerval itvs = { onceintv, startintv };
    setitimer(ITIMER_REAL, &itvs, nullptr);
    sigaction(SIGALRM, &start_act, nullptr);
    pause();

    setitimer(ITIMER_REAL, &itvw, nullptr);
    sigaction(SIGALRM, &lose_act, nullptr);

    for (; won == false; ) {
        for (size_t i = 0; i < letter_count; ++i) required[i] = chr[random_char_pos(re)];
        again = false;
        printf("Input: %s\n", required);

        for (; again == false; ) {
            fgets(input, input_capacity, stdin);
            if (strcmp(input, required) == 0) {
                won = true;
                break;
            }
        }
    }

    puts("YOU WIN!");
    return 0;
}