Error C2057: expected constant expression

Error C2466: cannot allocate an array of constant size 0

Error C2133: 'inc': unknown size

Why? Here's the code:

```
#include <stdio.h>
#include <stdlib.h>
#include <fftw3.h>
static double *rdata = NULL, *idata = NULL;
static fftw_plan rplan, iplan;
static int last_fft_size = 0;
double A[8192];
int n = 8192;
int i,m,k;
char erg[35];
char erg2[35];
double absval;
int is16bitfile = 1;
int main() {
double cc;
int v, val, val2;
char inc[n];
FILE *infile;
FILE *file;
FILE *file2;
int samplerate = 44100;
int bandwidth = samplerate / 2;
int nhalf = n / 2;
double correction = (double)samplerate / (double)n;
infile = fopen("theevent-zoom.wav", "r");
file = fopen("data.dat", "w");
file2 = fopen("data.raw", "w");
// skip wav file header
fgets(inc,37,infile);
fgets(inc,9,infile);
// read data and fill "A"-array
for (v=0;v<n;v++) {
val = fgetc(infile);
if (is16bitfile) {
val2 = fgetc(infile);
if (val2 > 127) { val2 = val2 - 255; }
A[v] = 256*val2 + val;
} else {
A[v] = val;
}
sprintf(erg2, "%d %f\n", v, A[v]);
fputs(erg2, file2);
}
// prepare fft with fftw
rdata = (double *)fftw_malloc(n * sizeof(double));
idata = (double *)fftw_malloc(n * sizeof(double));
// create the fftw plan
rplan = fftw_plan_r2r_1d(n, rdata, idata, FFTW_R2HC, FFTW_FORWARD);
// we have no imaginary data, so clear idata
memset((void *)idata, 0, n * sizeof(double));
// fill rdata with actual data
for (i = 0; i < n; i++) { rdata[i] = A[i]; }
// make fft
fftw_execute(rplan);
// post-process FFT data: make absolute values, and calculate
// real frequency of each power line in the spectrum
m = 0;
for (i = 0; i < (n-2); i++) {
absval = sqrt(idata[i] * idata[i]);
cc = (double)m * correction;
sprintf(erg, "%f %f\n", cc, absval);
fputs(erg, file);
m++;
}
// housekeeping
fclose(file);
fclose(file2);
fclose(infile);
fftw_destroy_plan(rplan);
fftw_free(rdata);
fftw_free(idata);
return 1;
}
```