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A little help with my code?

alexrider0820 (3)
Hello guys, I'm new to C++, the following code is a homework assignment and the compiler that I'm using is codeblocks' GNU compiler. When i try to run the code below, using the random number option and setting the length of the haystack to 13 or bigger (i.e. length>=13), the program just crashes and the computer pops out the "Windows is searching for a solution..." window. The program runs perfectly for length <=12 though, which is why I'm really confused. Help is much appreciated.

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  Put the code you need help with here.
//Needle in a haystack.
#include <iostream>
#include <math.h>
#include <stdlib.h>
#include <time.h>

using namespace std;

int main()
{
    //basic description
    cout << "This project aims to find a needle in a haystack." << endl;
    cout<<"We define a haystack as a random ordered 1-line array of numbers."<<endl;
    cout<<"We define a needle as an element such that all elements after the needle is smaller than or equal to in "<<endl<<"value to the needle."<<endl;
    cout<<"Please enter length of the haystack."<<endl;

    //length refers to the size of the array/haystack
    long int length;
    cin>>length;
    srand(time(NULL));

    //haystack is the array of size length
    //haystack[1][length] stores the elements
    //haystack[2][length] stores the max
    //haystack[3][length] stores the truth check if an element is a needle
    long int haystack[3][length];

    cout<<"Would you like the haystack to be randomly generated? (1/0)"<<endl;
    int option;
    cin>>option;
    cout<<"What is the maximum element permitted?"<<endl;
    long int max2;
    cin>>max2;
    //i is the loop counter for the 'for' loop.
    long int i;
    if(option==1){
        for(i=1;i<=length;i++){
            haystack[1][i-1]=rand()%(max2+1);
        }
    }
    else{
        for(i=1;i<=length;i++){
            cout<<"Enter the "<<i<<" number of the haystack."<<endl;
            cin>>haystack[1][i-1];
        }
    }







    cout<<"This is the haystack:"<<endl;
    //loop to display the contents of haystack.
    for(i=1;i<=length;i++){
        cout<<haystack[1][i-1]<<" ";
    }
    cout<<endl<<endl;

    //last element is defined to be a needle
    haystack[3][length]=true;

    long int max1;
    max1=haystack[1][length-1];

    for (i=1;i<=length;i++){
        cout<<"max1 = "<<max1<<endl;
        if(haystack[1][length-i]>=max1){
            haystack[3][length-i]=true;
            max1=haystack[1][length-i];
            cout<<"Term "<<length-i+1<<" = "<<haystack[1][length-i]<<" is a needle."<<endl;
        }
        else{
            haystack[3][length-i]=false;
            cout<<"Term "<<length-i+1<<" = "<<haystack[1][length-i]<<" is not a needle."<<endl;
        }
    }

    cout<<endl<<endl<<"The following terms are needles:"<<endl;
    //display loop
    for(i=1;i<=length;i++){
        if(haystack[3][length-i]==true){
            cout<<"The "<<length-i+1<<" term = "<<haystack[1][length-i]<<endl;
        }
    }

    return 0;
}
AbstractionAnon (6954)
Line 27: That's not valid C++. Fixed arrays must have dimensions known at compile time.
alexrider0820 (3)
Thanks for your assistance. But the problem has been solved. haha. The problem was that I used the wrong dimensions for the array. I defined a 3xlength array, but used the 4th row of the array as I forgot the row number starts at 0. thanks anyways
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