srand

I understand that rand() function generates the same number(s) each you run it if you don't change the seed number. That's where srand() comes in. Time is always changing so I know that you should pass the time(null) parameter to srand. My question is with the code below from a tutorial site. int main() { int i, n=5; time_t t; /* Intializes random number generator */ srand((unsigned) time(&t)); /* Print 5 random numbers from 0 to 50 */ for( i = 0 ; i < n ; i++ ) { printf("%d\n", rand() % 50); } return(0); } I see no link from the srand ((unsigned) time(&t)); and rand. printf("%d\n", rand() %

定义和用法 srand() 函数播种随机数生成器（rand()）。 提示 ：从 PHP 4.2.0 开始，随机数生成器自动播种，因此没有必要使用该函数 srand（seed）。 seed可选 时间函数time（） ：Return the time as seconds elapsed since midnight, January 1, 1970, or -1 in the case of an error. time（NULL），因为时间每秒都在变化，因此srand()里面的参数也时刻在变化，可以达到随机的要求！！！ #include <stdio.h> #include <stdlib.h> #include <time.h> int main() { srand((unsigned int)time(NULL)); printf("%d\n",rand() %10); // 0-9 printf("%d\n",rand() %11 +10); // 10 - 19 printf("%d\n",rand()); printf("%d\n",rand()); printf("%d\n",rand()); /*printf("%d\n",time(NULL));*/ return 0; } 来源： https://blog.csdn.net/weixin_44656803

When I used at first srand(time(NULL)) in rollDice() function it did not work. But when I put it in main, it works. Why is that? Can you tell me the logic? #include <stdio.h> #include <time.h> #include <stdlib.h> int rollDice(void) { return (1+rand()%6) + (1+rand()%6); } int main(void) { int roll; srand(time(NULL)); roll = rollDice(); printf("You rolled %d.\n", roll); enum Gamestatus {WON,LOST,CONTINUE}; enum Gamestatus status; while(status==CONTINUE){ printf("You are rolling again: \n"); printf("You rolled %d\n", roll = rollDice()); if (targetPoint==roll){ printf("You win!"); status=WON; }

This question already has an answer here: srand() — why call it only once? 7 answers My program contains code that should generate a random positive integer number every time I execute it. It generates random numbers but only once. After that, when I execute same code, it gives me same values, and it is making my code useless. I started with the rand function, and then I used the srand() function with the time.h header file, but still it is not working properly. #define size 10 for(i=0;i<size;i++) Arr[i] = rand()%size; First call (random): 6 0 2 0 6 7 5 5 8 6 Second call (random but same as

Hey guys take a look at this program. /* The craps game, KN king page 218 */ #include <stdio.h> #include <time.h> #include <stdbool.h> #include <stdlib.h> int roll_dice(void); bool play_game(void); int roll_dice(void) { int roll; getchar(); srand((unsigned) time(NULL)); roll = rand() % 13; if(roll == 0) roll = roll + 1; return roll; } bool play_game() { int sum = 0, wins = 0, loss = 0, point; sum = roll_dice(); printf("You rolled: %d", sum); if(sum == 7 || sum == 11) { printf("\nYou won!\n"); return true; } if(sum == 2 || sum == 3 || sum == 12) { printf("\nYou lost!!"); return false; } point =

So, I'm trying to create a random vector (think geometry, not an expandable array), and every time I call my random vector function I get the same x value, though y and z are different. int main () { srand ( (unsigned)time(NULL)); Vector<double> a; a.randvec(); cout << a << endl; return 0; } using the function //random Vector template <class T> void Vector<T>::randvec() { const int min=-10, max=10; int randx, randy, randz; const int bucket_size = RAND_MAX/(max-min); do randx = (rand()/bucket_size)+min; while (randx <= min && randx >= max); x = randx; do randy = (rand()/bucket_size)+min; while