Thread: What does the mean of error messages?

Code:

#include <math.h>
#include <stdio.h>
#include <stdlib.h>

void SpecialNumber(int n)
{
	FILE *fw;
	int i, j, k, d;
	int *a;
	d = 0;
	a = malloc(n*sizeof(*a));
	fw = fopen("SpecialNumber.out", "wt");
	for (i = 2; i < pow(10, n); i++) {
		for (j = 0, k = pow(10, n); k >= 10; j++) {
			a[k] = (int)(i%j)/(j/10);
			j/=10;
		}
		for (j = 0; j < n; j++) {
			d += pow(a[j], n);
		}
		if (d == i)
			fprintf(fw, "%5d", i);
	}
	free(a);
	fclose(fw);
}

int main()
{
	FILE *fr;
	int n;
	fr = fopen("SpecialNumber.dat", "rt");
	fscanf(fr, "%d", &n);
	SpecialNumber(n);
	fclose(fr);
	return 0;
}

Code:

mathsniper:~# gcc -O2 -o SpecialNumber SpecialNumber.c
/tmp/cc4zGvKf.o: In function `SpecialNumber':
SpecialNumber.c:(.text+0x56): undefined reference to `pow'
SpecialNumber.c:(.text+0x79): undefined reference to `pow'
SpecialNumber.c:(.text+0xe5): undefined reference to `pow'
collect2: ld returned 1 exit status

I have included the math.h but it show the error messages.