问题
I have a typical situation where I need to generate a batch of random numbers. I have used a loop which generates 100 random numbers on each pass:
for(int i=0; i<npasses; i++)
{
srand(time(NULL)); //Initialize seed
for(int j=0; j<100; j++)
printf("%d ", rand()%10);
printf("\n"); //New line after 100 numbers
}
Now, the inner loop executes in less than a millisecond. As a result, there is no change in the value of time(). This re-initializes the seed (srand()) to the same value and my random numbers are REPEATED..
Can anyone suggest a workaround/fix.
回答1:
Set the seed once, before the loop.
回答2:
Keep srand
out:
srand(time(NULL)); //Initialize seed
for(int i=0; i<npasses; i++)
{
for(int j=0; j<100; j++)
printf("%d ", rand()%10);
printf("\n"); //New line after 100 numbers
}
回答3:
try this
srand(clock()); //Initialize seed
回答4:
You can use the random generator to generate a new seed.
For example:
srand((unsigned int)rand());
And use srand(time(NULL))
only once before the loop. But as suggested in another answer, you might as well drop the whole srand
inside the loop as well.
来源:https://stackoverflow.com/questions/16585152/avoiding-repeated-seed-generation-using-srand