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carraysdynamic
Simol
Simol

Reputation: 639

Dynamic array in C cause segmentation fault

I have defined a dynamic array this way:

double   *n_data ;
int n_data_c = 0, n_cnt = 0;
n_data_c = count_lines_of_file("abnorm");
n_data = (double *)malloc(n_data_c * sizeof(double));

in a loop I calculate distance and do so: 

n_cnt++;
n_data[n_cnt] = distance;

but it returns segmentation fault here : n_data[n_cnt] = distance;

I want to know if I'm doing something wrong.

Upvotes: 0

Views: 96

Answers (4)

Nandan Bharadwaj
Nandan Bharadwaj

Reputation: 560

Just try printing the value of n_data_c before mallocing.

Upvotes: 0

G one
G one

Reputation: 2729

n_data_c = count_lines_of_file("abnorm");

this is generating the segmentation fault. Check the value of n_data_c

Upvotes: 0

Luke
Luke

Reputation: 707

Check what malloc returned, if it returned 0, then it failed. More likely, I think, is your n_cnt is out of bounds. If it's negative, or greater than or equal to n_data_c, then you'll get a segfault.

Upvotes: 3

Mukt G
Mukt G

Reputation: 101

You are overrunning your array buffer..

Compare n_cnt with n_data_c and only access the array if n_cnt < n_data_c/ 

n_cnt++;
if (n_cnt < n_data_c)
{
n_data[n_cnt] = distance;
}

Upvotes: 0

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