Thread: A few questions

  1. #1
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    A few questions

    Hi the first question is, how can I set a min and max for the rand function. At the moment i'm seeding from ctime then using
    Code:
    int theNumber = rand() % max + 1
    It picks a number between 0 and 100 then if its too high it sets the max integer to the number just guessed. How can I change the min one.

    My second question is:

    Code:
    #include <iostream>
    #include <string>
    #include <vector>
    
    using namespace std;
    
    int main()
    {
        string input;
        const int MAX_ITEMS = 10;
        int inventoryCount = 0;
        string inventory[MAX_ITEMS];
        vector<string> shopList;
        int shopListCount = 0;
        shopList.push_back("Sword") && (shopListCount++);
        shopList.push_back("Shield" && (shopListCount++);
        shopList.push_back("Firewood") && (shopListCount++);
        
        cout << "Welcome to Ben's Test RPG, input inventory if you want to see what you own, type quit to leave aand type shop to see the shop" << endl;
        
        
        do
        {
             cin >> input;
             
             if(input == "inventory")
                      
                      if(inventoryCount != 0)
                                        
                                        for (int i=0; i < inventoryCount; i++)
                                            
                                            cout << inventory[i];
                                        
                      else
                                        
                                        cout << "Sorry you have no items." << endl;
                                        
             
             if(input == "shop")
             
                      for (int j=0; j < shopListCount; j++)
                          
                          cout << shopList[j];
                      
             if(input == "quit")
             ;
             
             else
             
                 cout << "Sorry incorrect choice.";
                 
                 }while(input != "quit")
                 
                 }
    How can I make it so it adds to my shopListCount when the vector gets pushed back.

    Thanks,
    Ben

  2. #2
    Officially An Architect brewbuck's Avatar
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    Quote Originally Posted by Chipmunkey View Post
    It picks a number between 0 and 100 then if its too high it sets the max integer to the number just guessed. How can I change the min one.
    Imagine you could generate a random number between 0 and 50. Now add 50 to this number. You now have a random number between 50 and 100. Make sense?

  3. #3
    C++ Witch laserlight's Avatar
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    how can I set a min and max for the rand function
    Read Prelude's article on Using rand().

    It picks a number between 0 and 100 then if its too high it sets the max integer to the number just guessed.
    Your code snippet produces a number between 1 and max inclusive.

    How can I make it so it adds to my shopListCount when the vector gets pushed back.
    Just increment:
    Code:
    shopList.push_back("Sword");
    ++shopListCount;
    shopList.push_back("Shield");
    ++shopListCount;
    shopList.push_back("Firewood");
    ++shopListCount;
    Of course, since you are manually inserting 3 items, you might as well initialize shopListCount to 3.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  4. #4
    Registered User
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    Why do you need shopListCount at all? Just use shopList.size().

  5. #5
    Registered User
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    Code:
    shopList.push_back("Shield") && (shopListCount++);

  6. #6
    and the hat of sweating
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    Finally... A practical use for high school algebra.

    Well we know that rand() % num gives us a number from 0 to (num - 1). So after a few revisions and tests in my head, here's my final answer:
    (rand() % (max - (min - 1))) + min

    If min = 50 & max = 100 then:

    (rand() % (100 - (50 - 1))) + 50
    =(rand() % (100 - 49)) + 50
    =(rand() % 51) + 50
    =(0...50) + 50
    =(50...100)

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