Passing pointer to function - C programming

[thangviet]

Hey guys,
I have a function which needs to read a file and use the pointer parameter given.
the pointer is a structure with five members; int points, float *time, *dhdt, *drate and *diff.
The .dat file contains double values in three columns. I am required to open the .dat file, read the values and insert them into their appropriate members
(1st column of data into *time, 2nd column into *dhdt and 3rd column into *drate).
I have already dynamically allocated memory into the above members.
(data->time = (float *)malloc(sizeof(float), etc);
The variable "points" inside the structure is a user input which is used as the number of lines to read from the file
Here is my code:

File contains 1800 lines altogether
0.00000000               -314.18      -304.77
1.0000e-04    -423.69    -297.31
0.00020000    -259.91    -289.69
...
...
 
// (d) readData function
void readData(simData *data)
{
//open file coding
FILE *file_data;
int k;
 
if ((file_data = fopen("dissipate.dat", "r"))==NULL) {
printf("Cannot open file.\n");
exit(1);
}
else
{                    
while((fscanf(file_data, "%f %f %f", &data->time[k], &data->dhdt[k], &data->drate[k]))== 3);
 
}
fclose(file_data);
} 

how would you get the value of the 1st column to go into the time array?
I tried using a for loop to count through data->points times and print the values line by line but my program crashes.
Any help is much appreciated

[Banfa]

You haven't shown your memory allocation which is the most likely cause of the error, however it should be something like

data->time = (float *)malloc(sizeof(float) * data->points);
 

to get an array of the correct size.

[thangviet]

Thanks for your reply, I'll try that and get back to you on it.