Hi, I have written a c code that finds euclidean distance between corresponding elements of two 2D arrays. i have taken two text files like this..

9.0444 0.083404 -0.30599 -0.21367 -0.032527 -0.048789 -0.17683 -0.10523 0.050547 -0.028377 -0.06061 -0.0011242 -0.031838

9.164 0.18631 -0.3277 -0.1631 -0.014165 -0.041347 -0.063973 -0.059217 0.1422 -0.076865 -0.22507 -0.24214 -0.069154

9.1688 0.27382 -0.21322 -0.21558 -0.20094 -0.2459 -0.21811 -0.22654 -0.093443 -0.14375 -0.17468 -0.17559 -0.079262

8.9909 0.13161 -0.23827 -0.15121 -0.062505 -0.1702 -0.12139 -0.17619 0.035838 -0.089756 -0.17788 -0.089365 0.076777

8.9626 0.006085 -0.20092 -0.21606 -0.010768 -0.089176 -0.12807 -0.073935 0.081079 0.050701 -0.13336 -0.12325 -0.11199

Number of columns are fixed i.e 13 but rows can vary in millions. code is working well with small text files. But it is not working with large text files due to array size. i need to define array dynamically. but i don't know how to do it. This is what i have done so far..

```
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main(void)
{
int i=0,j,k,x,count=0,n=0,m=13,p=0,q=13;
float dis=0.0,s=0.0;
float avg[100],a[100][100],b[100][100];
//double dis=0,s=0,avg[100];
char buf[BUFSIZ];
FILE *fp1,*fp2,*fp3;
//clrscr();
fp1=fopen("a1.txt","r");
fp2=fopen("a2.txt","r");
//fp3=fopen("ouput.txt","w");
while (fgets(buf,sizeof(buf),fp1) != NULL)
n++; // counting rows of a1.txt
while (fgets(buf,sizeof(buf),fp2) != NULL)
p++; // counting rows of a2.txt
rewind(fp1);
for(i=0;i<n;i++)
{
for(j=0;j<m;j++)
{
fscanf(fp1,"%f",&a[i][j]);
printf("%f ",a[i][j]);
}
printf("\n");
}
printf("\n");
rewind(fp2);
for(i=0;i<p;i++)
{
for(j=0;j<q;j++)
{
fscanf(fp2,"%f",&b[i][j]);
printf("%f ",b[i][j]);
}
printf("\n");
}
printf("\n");
//calculation part
for(x=0;x<=(n-1);x++)
{
if(count!=(n-p)+1){
i=x;k=0;
while(i<(p+x))
{
for(j=0;j<q;j++)
{
s=s+pow((a[i][j]-b[k][j]),2.0);
dis=sqrt(s);
}
i++;
k++;
}
count++;
avg[i]=dis;
printf("\n\n%f\n",avg[i]);
s=0;
}
else
break;
fprintf(fp3,"%f\n",avg[i]);
}
//getch();
fclose(fp1);
fclose(fp2);
fclose(fp3);
}
```

Any help is appriciated...Thank you.