By mistake I wrote the followi

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By mistake I wrote the following program and it compiles and runs without any error in gcc compiler. enter code here

#include<stdio.h>
#include<stdlib.h>
int main()
{
int i,**data;
data=(int **)malloc(sizeof(int)*1000000);
for(i=0;i<1000000;i++)
data[i]=(int *)malloc(sizeof(int)*1000000);
printf("done\n");
return 0;
}
But I don't understand how is it allocating an array of 1000000*1000000 bytes,almost equivalent to 1TB??
- Amit January 28, 2014 in India | Report Duplicate | Flag | PURGE
SDE1 C

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Comment hidden because of low score. Click to expand.

of 1 vote

It's not. Some of those mallocs are returning NULL. C doesn't have exceptions that it can raise.

- Anonymous January 28, 2014 | Flag Reply

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of 0 vote

Check if malloc returns valid address or NULL.
Anyway, you will get memory violation error which accessing it.

- shsf January 28, 2014 | Flag Reply

Comment hidden because of low score. Click to expand.

of 0 votes

Yes, I forgot the NULL check. Malloc returns NULL after 140 rows. Thank you for pointing this

- Amit January 28, 2014 | Flag

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-1

of 1 vote

As you are using double pointer, so memory will be created in a 2x2 array.
so,
data=(int **)malloc(sizeof(int)*1000000);
in the above line, you are creating 1000000 rows and
data[i]=(int *)malloc(sizeof(int)*1000000);
here, for each row you are allocating 1000000 columns...

- Prashanth January 28, 2014 | Flag Reply

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