CODEWITHSUNDEEP
c++
user3347541
user3347541

Reputation: 27

random number generator does not give me a random number

#include <cstdlib>
#include <cmath>
#include <string>
#include <iostream>
#include <cstring>
#include <vector>

using namespace std;

int main()
{
    int size = 0;
    int test = 0;
    string phrase, sentence;

    test = rand() % 4 + 1;
    cout << "#" << test << endl;

    switch(test)
    {
    case 1:
    phrase = "thing";
    sentence = "computer science";

    case 2:
    phrase = "Subject";
    sentence = "math and science";

    case 3:
    phrase = "Subject";
    sentence = "pony and unicorn";

    case 4:
    phrase = "Subject";
    sentence = "dinosaurs and rhino";

    };

    cout << "The phrase is..." << phrase << endl;
    cout << "Here is your sentence..." << sentence << endl;

    int length;
    length = sentence.length();
    char letter;
    int arysize[length];

    for(int z = 0; z < length; z++)
    {
        arysize[z] = 0;
    }

    int count = 0;

    while(count != 10)
    {

    cout << "Enter a letter" << endl;
    cin >> letter;

    for(int j = 0;j < length; j++)
        {
            if(sentence[j] == letter)
            {
                arysize[j] = 1;
            }
            else if (sentence[j] == ' ')
                arysize[j] = 1;
        }

    for (int m = 0; m < length; m++)
    {
        if(arysize[m] == 1)
        {
            cout << sentence[m];
        }
        else
            cout << "_";
    }

    count++;
    cout << "You have " << 10 - count << " tries left." << endl;
    }
}

Sorry for this mess because I was creating a sample and was doing trial and error to get the outcome. When I use the rand() with 4 + 1, I should get a number between 1 -4. But whenever I run the program, I always get 4. How come it does not randomly select a number but instead, always giving me the same number?

THanks guys! Just to make sure that if anyone else is reading... you have to include the

#include <ctime>

header in order for it to seed.

Upvotes: 1

Views: 187

Answers (2)

imreal
imreal

Reputation: 10378

Probably because you are not seeding it. Try using srand() before your first rand() call like this:

srand (time(NULL));

Upvotes: 4

aaazalea
aaazalea

Reputation: 7930

You need to seed the random number generator before you use it. Try inserting this line before you use rand() the first time:

srand (time(NULL));

That will seed the random number generator with the current time, allowing for more random values.

This answer talks about why you need to seed the random number generator.

Upvotes: 3

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