Same random characters generated every time in C++

Question

I am trying to write a code to return random character so I write the following code:

static char prepare-data()
{
    Sleep(rand()%500); // sleep random amount
    int n = rand()%26;
    char c = (char)(n+65);
    return c; // return random character
}

static void writer()
{
    int i, writePt = 0;
    char data;
    for (i = 0; i < data_length; i++)
    {
        data = preparedata(); // go off & get data ready
        buffers[writePt] = data; // put data into buffer
        cout<<"writer thread: buffer["<<writePt<<"]="<<data<<endl;
        writePt = (writePt + 1) % num_total_buffer;
    }
}

but every time I run the code I get the same characters is this considered as problem

Provide a seed to the random number generator in the beginning of your program. srand( time(NULL) ); — Abhishek Bansal, Mar 27 '14 at 05:20
You need to see the random number generator. This problem appears on SO almost daily. — Floris, Mar 27 '14 at 05:20
It is only a problem if you want a different random number each time... See http://xkcd.com/221/ — Floris, Mar 27 '14 at 05:25

score 4 · Answer 1 · answered Mar 27 '14 at 05:22

4

Maybe you want to add

/* initialize random seed: */
  srand (time(NULL));

before using rand()

answered Mar 27 '14 at 05:22

Yuanhang Guo

466
4
9

Yes, but this is covered in the duplicate questions linked above. No need to answer again. – Floris Mar 27 '14 at 05:23
You are right and I will delete this answer. – Yuanhang Guo Mar 27 '14 at 05:27
1

@YuanhangGuo No need to delete it. The topic will be closed eventually. In the meantime, enjoy the rep you're getting from the upvotes. You don't have much atm, you could use it. :P – cf- Mar 27 '14 at 05:32

Same random characters generated every time in C++

1 Answers1