Question

我应该给一个数字传递给thread_mutex初始化函数，以用作usleep（）的rondom种子生成器。我不知道为随机数创建种子意味着什么。我在使用srand（）时遇到的问题是将代码：srand(timeDelay)放在for循环中会使rand（）始终相同。直接指示说：

This action happens repetitively, until its position is at FINISH_LINE:
//   Randomly calculate a waiting period, no mare than MAX_TIME (rand(3))
//   Sleep for that length of time.
//   Change the display position of this racer by +1 column*:
//     Erase the racer's name from the display.
//     Update the racer's dist field by +1.
//     Display the racer's name at the new position.

码

int main( int argc, char *argv[] ) {
...
long int setDelay = strtol(argv[1], &pEnd, 10);
if ( setDelay == 0 ) {  
        //printf("Conversion failed\n");
        racersNumber = argc-1;
        setDelay = 3;
...
} else {
        //printf("Conversion SSS\n");
        racersNumber = argc-2;
        }
...
initRacers( setDelay);
for (idx = 0; idx < racersNumber; idx++) {
            printf("Thread created %s\n", racersList[idx]);
            //make a racer arra or do I add a pthread make function?
        rc = pthread_create(&threads[idx], NULL, run, (void*) makeRacer(racersList[idx], idx+1));
...

init赛车的代码生成“随机种子”

static pthread_mutex_t mutex1; static long int timeDelay; void initRacers( long distance) { printf("Setting the time delay\n"); //set the mutex pthread_mutex_init(&mutex1, NULL); timeDelay = distance; }
运行功能的
代码

#define MAX_TIME 200 // msec void *run( void *racer ){ //pre-cond: racer is not NULL if ( racer == NULL ) { return -1; } //convert racer back to racer for (int col = 0; col < FINISH_LINE; col++ ) { Racer *rc; //conversion rc= (Racer*)racer; pthread_mutex_lock(&mutex1); if ( col != 0 ) { set_cur_pos(rc->row, col-1); put(' '); } set_cur_pos( rc->row, col); pthread_mutex_unlock( &mutex1 ); //loop function for each at same column for (int idx = 0; idx < sizeof(rc->graphic); idx++) { put(rc->graphic[idx]); } //srand(timeDelay); usleep(100000L*(rand()%timeDelay)); } }

Answer 1

“将代码：srand（timeDelay）放入for循环”。您没有将srand()放入循环中。你在程序开始时调用它一次，通常使用时间参数，因此每次运行程序时从rand（）获得的随机序列都是不同的。

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

int main()
{
    int i;
    srand ((unsigned)time(NULL));
    for (i=0; i<5; i++)
        printf ("%6d", rand());
    printf ("\n");
    return 0;
}

如何在for循环中为pthread函数usleep（）使用随机种子生成器？

1 个答案: