C program won't get access to textile - c

Question

Just to make it clear - I'm a beginner in C.
When my program is running (using Xcode), no values correspond to the values in "resultfortran.txt". Instead, they become very small, very large or zero (looks random). For example, the variable n becomes 0, even though the first line in "resultfortran.txt" is 10. The variables min and max also becomes very small (and don't get the values at line 2 and 3).
I have searched the web all day, and asked my fellow students. If it is of interest, I got the error "EXC_BAD_ACCESS" on the line where the file is opened, but that error has (some how?) disappeared. And yes, "resultfortran.txt2 is in the same folder as main.m.
The start of the program is shown below:
#include <assert.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <GLUT/glut.h>
#include <OpenGL/OpenGL.h>
#include <Cocoa/Cocoa.h>
static void draw( void )
{
int n,i,j;
float step,min,max,x,y,scaled;
float matrix[1000][1000];
FILE *fp; //reads input file
fp=fopen("resultfortran.txt", "r");
fscanf(fp,"%d",&n); //Gives n the value of the first line.
step=(1.0/n); //Defines step size
fscanf(fp,"%f",&min); //Gives min the value of the second line.
fscanf(fp,"%f",&max); //Gives max the value of the third line.
for (i=0;i<n+1;i=i+1)
{
for (j=0;j<n+1;j=j+1)
{
fscanf(fp,"%f",&matrix[i][j]);
}
}
... not finished here ...
The first lines of the file "resultfortran.txt" (which is a output from a fortran script) is shown below:
10
0.00000000
0.500000000
0.0000000000
0.0025000002
0.0100000007
0.0225000009
0.0400000028
0.0625000000
0.0900000036
0.1224999949
0.1600000113
0.2024999857
0.2500000000
0.0025000002
0.0050000008
0.0125000002

Answer 1

Since you're "a beginner in C", I want to first welcome you to what is a very rigorous but rewarding language. Though, to be fair, I wouldn't consider someone who is writing operating system code to be a "beginner" in C.
I'll gladly assist you and update this answer as we proceed. My first suggestion is as follows:
The first thing you always should do when doing file operations (like opening one) is to check the results of the execution! For example, if you read the man page on fopen(), you'll see that fopen() will
return a FILE pointer. Otherwise, NULL is returned and errno is set to
indicate the error.
So, use something similar to the code below to make sure that your file is opening as expected:
if (fp == NULL) {
printf("fopen did not work! Check errno %d\n", errno);
}
else {
printf("fopen workd!\n");
}
I will update this answer once you get back to me on the results of implementing the code above.