Thread 1: EXC_BAD_ACCESS (code=1, address=0x68) when trying to open a file

Question

So I tried to open and read a file this way but I get:

Thread 1: EXC_BAD_ACCESS (code=1, address=0x68) it says that the pointer is null

This is my code:

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

int main(int argc, const char * argv[]) {
    
    FILE * fp;
    
    fp = fopen("labb.txt", "r");
    
    char line[200];
    
    while(!feof(fp)){
       
            fgets(line, 200, fp);
            puts(line);
        
        
    }fclose(fp);
    
    return 0;
}

fp is null i tried multiple ways to call the file but none seem to work — nicolas rollino, Sep 25 '20 at 10:09
Switch to `while (fgets(line, 200, fp)) { puts(line); }` and see [Why is “while ( !feof (file) )” always wrong?](https://stackoverflow.com/q/5431941/1606345) — David Ranieri, Sep 25 '20 at 10:14
make sure that the file labb.txt is in the project folder. try to make new file (`fp = fopen("labb.txt", "w");`) and wirte to it, after that run the origin code to check if it work — jacob galam, Sep 25 '20 at 10:15
@jacobgalam ***no!*** That will overwrite the file and erase all the content. OP is trying to read data from it, so that's not a good idea. — Marco Bonelli, Sep 25 '20 at 10:16

Marco Bonelli · Accepted Answer · 2020-09-25T10:19:58.947

I see at least three problems in your code:

This is not going to work:
```
fp = fopen(fileLocation, "r"); // fileLocation is "~/Desktop/labb.txt"
```
The C library stdio functions do not know what ~ is. It's not going to expand ~ for you. You should expand it yourself or change method. See this post for more information.

If the file is in the same directory as the one you are running the program in, you can use ./labb.txt. If not, you can always use the absolute path to the file, or figure out a correct relative path. E.G. if labb.txt is in /home/you/Desktop and your program is in /home/you you should use ./Desktop/labb.txt.
You do not check for errors. You should check fp != NULL after the call to fopen. Opening a file can always fail, always check for errors.
```
fp = fopen(...);
if (fp == NULL) {
    perror("fopen failed");
    return 1;
}
```
The same goes for fgets, reading a file can always fail.
```
char *res = fgets(line, 200, fp);
if (res == NULL) {
    perror("fgets failed");
    return 1;
}
```
while (!feof(fp)) is always wrong: see this answer to understand why.

Thread 1: EXC_BAD_ACCESS (code=1, address=0x68) when trying to open a file

1 Answers1