Help me fix an array declaration program in C++

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manish12

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Array declaration in C++

WHY THIS PROGRAM DONT WORK?

Here if I declare arr[100][100] then it works, but if I increase array size to 1000, it don't?


#include<iostream>
using namespace std;

int main()
{
int i,j;
double arr[1000][1000];
for (i=1;i<=1000;i++)
for(j=1;j<=1000;j++)
cout<<a[j]<<endl;
return 0;
}
 

Re: Array declaration in C++

100 * 100 = 10,000 items in the array (0x2710), 10K * 8 bytes = 80 Kbytes
1000 * 1000 = 1,000,000 items in the array (0xF4240), 1M * 8 bytes = 8 Mbytes

Too large of array?
Does 250 x 250 array work (250 * 250 = 62500 or 0xF424)?
Does 300 x 300 array fail (300 * 300 = 90000 or 0x15F90)?
 

Array declaration in C++

You should use memory allocation functions instead of array for big data.

double *p = new double[1000*1000];

works well.
 

Re: Array declaration in C++

Well, [1000] [1000] is just too big!!!! As “rmitoday” says try memory allocation
 

Re: Array declaration in C++

Always use the dynamic allocation of memory for the large data size
use the malaloc fun
 

Re: Array declaration in C++

#include<iostream>
using namespace std;

int main()
{
int i,j;
double arr[1000][1000];
for (i=1;i<=1000;i++)
for(j=1;j<=1000;j++)
cout<<a[j]<<endl;
return 0;
}

size of 1000 means go from 0 to 999, so use this

for (i=0;i<1000;i++)
for(j=0;j<1000;j++)

Rolf
 

Array declaration in C++

u're right rolf,
 

Array declaration in C++

don't be forget to initial those variable, a[][], before using them in the cout << ...;
 

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