You need to call srand()
once, to randomize the seed, and then call rand()
in your loop:
#include <stdlib.h>
#include <time.h>
#define size 10
srand(time(NULL)); // randomize seed
for(i=0;i<size;i++)
Arr[i] = rand()%size;
質問
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 previous):
6 0 2 0 6 7 5 5 8 6
Later I visited Stack Overflow questions and I read about the srand() function, and I used it as:
#include<time.h>
for(i=0;i<size;i++)
Arr[i] = srand(time(NULL));
First call:
-10327 -10327 -10327 -10327 -10327 -10327 -10327 -10327 -10327 -10327
Second call:
-10326 -10326 -10326 -10326 -10326 -10326 -10326 -10326 -10326 -10326
It is giving me different (but not random values). I've defined Arr[i] as unsigned int, and still I am getting negative values.
解決
You need to call srand()
once, to randomize the seed, and then call rand()
in your loop:
#include <stdlib.h>
#include <time.h>
#define size 10
srand(time(NULL)); // randomize seed
for(i=0;i<size;i++)
Arr[i] = rand()%size;
他のヒント
Try to call randomize() before rand() to initialize random generator.
(look at: srand() — why call it only once?)
If you chose to srand
, it is a good idea to then call rand()
at least once before you use it, because it is a kind of horrible primitive psuedo-random generator. See Stack Overflow question Why does rand() % 7 always return 0?.
srand(time(NULL));
rand();
//Now use rand()
If available, either random
or arc4rand
would be better.
#include"stdio.h"
#include"conio.h"
#include"time.h"
void main()
{
time_t t;
int i;
srand(time(&t));
for(i=1;i<=10;i++)
printf("%c\t",rand()%10);
getch();
}
#include"stdio.h"//rmv coding for randam number access
#include"conio.h"
#include"time.h"
void main()
{
time_t t;
int rmvivek;
srand(time(&t));
rmvivek=1;
while(rmvivek<=5)
{
printf("%c\t",rand()%10);
rmvivek++;
}
getch();
}