Arrays!!!

This is a discussion on Arrays!!! within the C++ Programming forums, part of the General Programming Boards category; If we have this : Code: #include <iostream.h> #include <stdlib.h> int main() { const int size=7; int a[size]={0}; for( int ...

  1. #1
    Registered User
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    Jan 2006
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    Jerusalem
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    Question Arrays!!!

    If we have this :
    Code:
    #include <iostream.h>
    #include <stdlib.h>
    int main()
    {
    const int size=7;
    int a[size]={0};
     for( int i=1; i<600; i++)
      ++a[1+ rand()%6];
      cout<<a[i]<<endl;
      for(int j=0; j<size; j++)
        cout<<a[j]<<" ";
    the out put would be like that:
    Code:
    0
    9404  9063  14109  9306  18378  9454
    why the value of the array remained 0 while i have already incremet it and also i have used rand()???
    and wut are these numbers when the array is being printed in the second loop? why the each cell contains 4 or more numbers? why not one number? and why does it conttain 7, 8 and 9 if i used the rand() of range (0-6)?????????
    anyone can tell me?

  2. #2
    60% Braindead
    Join Date
    Dec 2005
    Posts
    379
    Code:
    #include <iostream>
    #include <stdlib.h>
    using namespace std; //Remove .h from iostream and use this namespace instead.
    
    int main(){
    const int size=7;
    int a[size]={0};
    int i, j;
    
     for(i=1; i < 600; i++) {
      ++a[(rand() % 6) + 1];
      cout<<a[i]<<endl;
     }
     for(j=0; j < size; j++)
        cout<<a[j]<<" " << endl;
    }
    I'm pritty sure your program was being confused from the lack of syntaxs. Remember to include the "{" "}" and "(" ")". I think that should fix the program.

    Not sure if thats what you wanted it to do though .
    Code:
    Error W8057 C:\\Life.cpp: Invalid number of arguments in function run(Brain *)

  3. #3
    Cat without Hat CornedBee's Avatar
    Join Date
    Apr 2003
    Posts
    8,893
    Blackroot, in three attempted answers I've seen of you today you've been at least partially wrong three times. You might want to learn a bit more first.

    That said, you are right that the formatting of the program leads to confusion - but only for the programmer, not the compiler. Confuse the compiler, and it give you an error.
    You are also right about the old-style headers.

    As for the program:
    Code:
    #include <iostream>
    #include <cstdlib>
    #include <ctime>
    using namespace std;
    
    int main()
    {
      srand(time(0)); // Initialize pseudorandom number generator. Without this, you'll get the
        // same result every run.
      const int SIZE = 7; // Typical naming convention is to put constants in all upper case.
      int a[SIZE] = {0};
      for(int i = 1; i < 600; ++i) { // Good practice to use prefix ++ unless postfix is required.
        int index = rand() % SIZE; // 1+rand()%6 would yield numbers from 1 to 6. Array indices
          // start from 0, though.
        ++a[index];
        cout<<a[index]<<endl; // Must use the same index here - i will be quickly out of bounds.
      }
      for(int i = 0; i < size; ++i) { // Unless you use a broken compiler, there's nothing wrong
             // with reusing the variable name here. (VC++, enable "for-scope" in the language
             // options.)
        cout << a[j] << " ";
      }
    }
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

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